Looking at Turbo charging my 3.4 DOHC engine, I began wondering about a turbo specific grind for my cams and it led to the following discussion that was eating up some serious space on my build thread https://www.fiero.nl/forum/Forum2/HTML/102001.html so I moved it here.

I was trying to work out some common trends with turbo cams vs naturally aspirated cams for the same engines.
The Idea here is to look at engines that come NA as well as turbo charged from the factory and compare the numbers to see if valve opening and closing events are earlier or later on turbo cams.
If these trends are consistent from engine to engine I should be able to covert them into percentages, for example if I look at 5 different turbo engine cam specs and all 5 open the intake valve later, I can assume that opening the intake valve later is standard for turbo cams and so on.
If I then take all 5 engines and figure how much later they open as a percentage vs the NA cams, then averaging them should give a ball park number, for example all 5 turbo engines open their intake valves 10% on average later than the NA versions then I should be able to apply that number to my project.

Here are some numbers for Mitsubishi eclipse 2.0 DOHC NA stock cam and a mild Turbo cam.

NA IVO -14 ATDC = The valve opens -14 ATDC
TC IVO -8 ATDC = The Turbo cam opens later by 6 degrees (Later)

Reference
-14 means ATDC actually means 14 BTDC and -8 ATDC is actually 8 BTDC
This means that the turbo cam opens the valve later.

NA EVO 26 BBDC = The valve opens 26 degrees BBDC
TC EVO 40 BBDC = The valve opens before the NA cam by 14 degrees (sooner)

NA IVC 18 ABDC = The valve closes 18 degrees ABDC
TC IVC 32 ABDC = The valve closes later the NA cam by 14 degrees (Later)

NA EVC -22 BTDC = The valve opens -22 degrees BTDC
TC EVC -16 BTDC = The valve opens before the NA cam by 7 degrees (sooner)

Reference
-22 means BTDC actually means 22 ATDC and -8 BTDC is actually 8 ATDC
This means that the turbo cam opens the valve sooner.

We see in this example that the turbo intake valves open later and close later than the NA cam.

We also see that the turbo exhaust valve opens sooner and closes sooner than a NA cam

NA TC
LCA 110 114
ICL 106 110

We can see that the LCA for the NA cam is 110 and the turbo cam gets an increase of 4 to make it 114.

We can see the ICL for the NA cam is 106 and the turbo cam gets an increase of 4 to make it 110.

What I have learned from this example:

Intake valves open and close later than NA cam.
Exhaust valves open and close sooner than a NA cam.
The turbo cam sees an increase in LCA vs the NA cam
The turbo cam sees an increase in ICL vs the NA cam.

I will now have to search out other DOHC engines an apply the same math to see if it holds true for other DOHC engine examples.

Thanks for the interest.
Numbers sourced from Crower.com

While looking for cam specs I ran across some 35mm VW/Audi lifters both hydraulic and solid. These lifters should slide into the 3.4 DOHC lifter bores and come in several heights. The question is what height are the stock 3.4 lifters???

If the VW/Audi lifters are taller and the oil hole is close, this could allow for a lot more material for a cam regrind. Right now us DOHC guys are limited by the stock cam profiles and how much they can be re-ground, with a taller lifter the cams would have extra material on all lobes allowing for the desired grind specs instead of what you can get out of the cams.

Anyone with the height specs or observations is welcome to respond.

quote Originally posted by Scoobysruvenge: While looking for cam specs I ran across some 35mm VW/Audi lifters both hydraulic and solid. These lifters should slide into the 3.4 DOHC lifter bores and come in several heights. The question is what height are the stock 3.4 lifters??? If the VW/Audi lifters are taller and the oil hole is close, this could allow for a lot more material for a cam regrind. Right now us DOHC guys are limited by the stock cam profiles and how much they can be re-ground, with a taller lifter the cams would have extra material on all lobes allowing for the desired grind specs instead of what you can get out of the cams. Anyone with the height specs or observations is welcome to respond.

You can't say "us DOHC guys" until you complete and install an engine in your car. Just thought I'd take a crack at you. You really need to visit the 60 degree V6 forum, they have a section set aside specifically for this engine alone.

Joe,

I looked around on the 60D site and found some useful information on lifters but could find no lifter height, I will call GM and see if they list the specs for the 35mm lifters.

The problem is that there is very little hard data, although there is some it is mostly conjecture and some measurements taken by a few shade tree mechanics.

I have never seen an engine in fact with so little hard data available on line.
I am currently looking around for a factory GM service manual for one of these cars, it should have a lot of the specs I am interested in.

As far as the “us” thing goes, you are correct I have not swapped one of these engines yet, nor do I even have an engine in my possession yet, but all that is about to change (see my Turbo thread post latter today)

Make no mistake all my chips are in this DOHC game and I am playing to win.

Glad to see someone having fun with it, thanks for the interest Joe

what is it you are looking for?
info for a custom grind? most places which do custom grinds have the info already
or looking for the best off-the-shelf cams for a turbo build? a 3.4 DOHC is quite a costly engine for this - 4 cams to replace
tho - I'd expect there maybe MUCH power to be found in modifying the cam timing - be it in advancing the intake or retarding the exhaust, whichever to eliminate the overlap (my guess is retarding the exhaust)

I’m looking for the height of the stock lifter, if the stock lifter is used I am stuck with how much the factory cam specs can be altered, you can always grind some off the factory cam to get different specs but you can’t add to the profile if you need because there is no extra material.

If a taller lifter is used it means that all the lobes on the cam have too machined down to accept the taller lifter giving me positive material if I want to increase lift for example.
First and foremost I really want is to increase the LSA/LCA of the cams to be a little more turbo friendly among other things.

I plan to regrind the cams, the price is 100 $ a cam so that’s 400 smackers, lots of cam companies will grind what they think you need on some base numbers, but the truth is that you need good head flow numbers before you ever consider a grind or a profile to make sure you have enough CFM to support the inflated cam numbers.

I am uninterested in how high the RPM needle goes, I am looking for a smooth linear pull to the redline not the peaky motor with all the juice in one spot that so often comes with extreme cam specs.

My cam specs should be mild but should also be far from the stock profile.

Thanks for the interest

while I agree flow head flow #'s help - they are fixed. unless you've ported the heads. in which case, did the guys who ported them give you new flow numbers, or will you be getting flow tests done?

anyways - I dunno much about the DOHC motor - but, would not just retarding the exhaust cam eliminate the intake/exhaust overlap, and make the stock cams that much better? or are the cams mixed intake/exhaust?

tho, I do like the idea of the larger lifters to allow the re-grind

Retarding the exhaust would increase overlap.

I don't see how lobe separation angle is relevant to a DOHC???

Anyway, it's unwise to make generalizations about whether more or less overlap is good.

This will depend on the intake:exhaust pressure ratio.

This is largely dependent on the turbine's A/R and trim.

The most important thing is to get the max area under the lift curve. You can play around with the phasing after the fact.

Edit: good read:
http://www.turbomagazine.co..._shootout/index.html

[This message has been edited by pmbrunelle (edited 12-08-2009).]

No have not had the heads worked yet, but I plan on having them cleaned up but no serious porting.
I have only some flow numbers posted on the 60D site and I’m not sure what year heads they are for or what size bore they used when measuring it, so those numbers are only good for speculation.
Retarding and advancing the cams is another method for tuning the engine but it is far from what grinding the cams can achieve. Combining these two methods should prove potent.
The subjects of overlap, duration, lift and valve events is the reason for starting this thread, but as I am finding out there is lot to camshaft specification selection.
What I am finding is that a blank statement like Turbo cams are small overlap, short duration in general can be dangerous.
Most of the engine/cam combos NA vs Turbo I find that the Turbo cams have a longer duration and more overlap than the NA cam for the same engine.
I also find that the LSA/LCA is 99% of the time increased when comparing a NA vs Turbo cams.
It also seems that on the engines I have looked at that the trend of opening the valve sooner and closing it later seems to be the norm, but I have a lot more research to do before I can speak with authority on the subject of the cam specs I will use.

Thanks for the interest and the info.

quote Originally posted by pmbrunelle: Retarding the exhaust would increase overlap. I don't see how lobe separation angle is relevant to a DOHC??? Anyway, it's unwise to make generalizations about whether more or less overlap is good. This will depend on the intake:exhaust pressure ratio. This is largely dependent on the turbine's A/R and trim. The most important thing is to get the max area under the lift curve. You can play around with the phasing after the fact. Edit: good read: http://www.turbomagazine.co..._shootout/index.html

wasnt sure which way that went - but anyways - isnt overlap the main concern on a turbo grind? the 2nd item being a long intake duration?
and, the intake/exhaust pressure - the exhaust is mostly going to have greater pressure. it has to - being it creates the intake pressure.
but - yes - I am only generalizing, and no expereience. trying to get a feel for this myself.
basicly I assumed the intake & exhaust were maxxed, with no overlap, being there is no scanvegning going on, and all intake & exhaust movements are pushed, and need no help from the cams.

I too am building a turbo 3.4 DOHC but using a 2.8 crank( 3.0L ) and 6" SBC H-beam rods and custom pistons. I am also using 1978 VW Rabit Lifters. The problem you will run into is that you need longer valves. I'm using Manley Race Master SS valves for a Ford 4.6 Modular I don't have the part numbers handy, but some machining to the valve head is required. BTW Im using BMW 528 manganese bronze valve guides.

Crower reground my cams for me here are the specs

Duration Lift Clearance Hot
intake 294 .408 .012
exhaust 290 .408 .014

@.050
intake 252 .408
exhaust 248 .408

intake opens 18.0 BTDC
closes 54.0 ABDC
Exhaust opens 60.0 BBDC
closes 8.0 ATDC

intake centerline 108


I'm planning on reving this motor That's why the big CAM


Steve P

This may sound crazy but what I am shooting for here is not a high RPM screamer but something that pulls more like a truck (a really fast truck) right off the bottom with a nice fat torque curve all the way up no spikes in power.

I am only speaking from research not actual experience but adding stroke to the engine should have just this effect, coupled with the turbo the engine should gain some low end power that is lacking in its stock configuration.

A de-stroked DOHC sounds interesting, what’s the science behind your engine configuration?

What kind of boost do you plan to run?

Can you explain the longer valve requirement in more detail ???

Thanks for the cam numbers, can you be more specific on what info you gave Crower to grind your cams.

Were the taller lifters able to give you much material to work with??

Questions, Questions, Questions

Do you have a thread here on PFF???

Thanks for the input.

So many questions

A de-stroked DOHC sounds interesting, what’s the science behind your engine configuration?

- Short Stroke, Long rods good for high RPM ( I like high rpm motors, not interested in drivability, it's a toy car for playing )

What kind of boost do you plan to run?

- 20 PSI

Can you explain the longer valve requirement in more detail ???

- the stock lifters from the cam lobe face to the the valve stem is thicker than the VW/Audi bucket lifters

Thanks for the cam numbers, can you be more specific on what info you gave Crower to grind your cams.

- I gave Crower all the engine data and stock flow numbers (from 60*V6) and that it was a toy car and to be street driven sometimes, and that
drivablity was not an issue

Were the taller lifters able to give you much material to work with??

- overall height of the VW/Audi lifters is the same as stock, Once you get one of each stock and VW/Audi lifter in you had you will see what I'm taking
about, The VW/Audi lifter is very thin between valve stem and cam lobe face, hence the longer valve stems

Looks like you are gearing up for some fun Spearce, thanks for the numbers they are greatly appreciated now if I could only compare them to the stock numbers…

PFF Member Spearce Crower Grind w/VW Lifters
@.050
intake 252 .408
exhaust 248 .408

IVO 18.0 BTDC
IVC 54.0 ABDC
EVO 60.0 BBDC
EVC 8.0 ATDC

60D website post stock cam specs 96-97 3.4 DOHC
.050 specs

Intake 205.1 duration, Exhaust 210 duration
IVO -7.5
IVC 32.5
EVO 35
EVC -5

The problem here is are the stock valve opening and closing referenced the same for example are both IVO numbers referenced at BTDC, the 60D numbers do not indicate where the valve was referenced.

I’ve looked at a lot of cam specs over the past few weeks and what I find is that these references change from engine to engine. If anyone can reference the stock numbers please post them here BTDC, ATDC and so on.

If the valve events are referenced at the same times for both of these cams it seems Crower sees a lot of room for performance if the difference in numbers is any indication.

These numbers are much farther apart the I would have imagined, here is also another example of a turbo cam having a larger duration and overlap than its NA counterpart.
Everything I read on turbo cams indicates low duration and low overlap… What Gives???

Keep in mind that My Crower cams are engineered for max power between 8500 and 9500 RPM and max torque around 6500 RPM. With the bosst I will be running. I'm told torque will still be above 200 lb.ft. at 2500 RPM. Max torque is only expected to be about 350 lb. ft.

This is not the type of cam you are looking for.

Everything i have read suggests that the stock cam(s) will give very good results when turbocharging a N.A. engine.

my engine is being built specifically for turbochaging C.R. 8.3:1 , forged where ever I can, lots of modifications, in fact the only unmodified pieces are the cam carriers and the block (the main caps are machined for tie straps and a girdle)


Steve

Spearce,

I am looking for a taller lifter, not a shorter one. I saw several 35mm lifters for VW/Audi engines.
I see why you used the taller valves now, but I hope to avoid replacing the valves with longer ones by using a taller lifter height (not the body but the valve contact point)
Did you research finding a taller lifter and how did you come up the the valve and lifter combo you a using.

Sorry for all the questions, but you are the only person I know messing around with the cams in this way that I know of.

The engine I started with had tuliped valves and they need replacing anyway. I was more concerned with getting lifters that would fit the lifter bore. The it was just measuring and searching the internet and catalogs for 7mm valves that were long enough. Anyone else watch this thread be aware that when you grind the cams the base circle is smaller and the lifters move toward the cam by the amount of the reduction of the base circle.

So the short answer is no I did not look at taller lifters, but I did consider modifying the stock lifter to be solid not hydraulic.

I have a friend who is an engine builder/hotrodder. Back in the day they used to do this with Fords and SBC. I've even found references on the internet of this being done on late model Mustangs with the 4.6 SOHC and DOHC


Steve

quote Originally posted by pmbrunelle: Retarding the exhaust would increase overlap. I don't see how lobe separation angle is relevant to a DOHC??? Anyway, it's unwise to make generalizations about whether more or less overlap is good. This will depend on the intake:exhaust pressure ratio. This is largely dependent on the turbine's A/R and trim. The most important thing is to get the max area under the lift curve. You can play around with the phasing after the fact. Edit: good read: http://www.turbomagazine.co..._shootout/index.html

No knock at you, but that was a poorly written article from a research standpoint. Posting comparison graphs without cam and turbo specs and referencing a radical cam providing minimal to less than stellar results again without cam specs is useless. You need those numbers to have a good idea of where your own platform stands from a relative inference. Some discussion was had in an earlier thread basically stating that much of the advice found in print and elsewhere is from the old "rule of thumb", without application of how exhaust back pressure and intake flow is what really determines what a good LSA should be for a camshaft and likewise for duration and lift. Without the help of sophisticated equipment and GM inside information, the best approach to determining a good cam spec is to start with your stock cam and carefully improve from there.

Scooby if you want a stump pulling cam then increased duration is probably not going to be the best path, especially since a properly sized turbo will add about 500 or so rpm on top of your stock HP peak. I would focus on optimizing airflow in areas other than the cam first and then make sure I'm running as much static compression as I can get away with. I've also changed my focus regarding my cam. The stock OE performance range is fine and since my focus is 0-60 my next regrind will focus what has already been mentioned, increasing area under the curve which can be done without increasing the duration. Another important area is larger exhaust valves for my engine anyway and an important point on exhaust flow is that increased lift on the exhaust lobe is not as effective as increased exhaust valve area simply because according to tests the bulk of the exhaust escapes within the first few degrees of the exhaust valve lifting off the seat. It's just the opposite on the intake end since flow is increasing as the intake valve lifts off the seat.

Joe,

Knowing you, you have done your homework on needing a larger valve in your engine but when I was working on the TGP I bought a set of the 3400 heads with the larger runners, ports and valves always thinking about getting the most air into the engine as possible, but after some reading I’m not sure it would have been better than the smaller valve and port heads due to what I’ve read about keeping velocities high and the advantage of small runners and valves in turbo engines.
There is no doubt that increasing valve size and using larger port heads and intakes can make more HP and some engines have more fat to trim than others, but at what cost across the RPM range will more air cost.
So a year after starting this project my perspectives have changed, I am not looking for the most HP I can get, I am looking to use all the HP I have.
300 + HP in a car like a Fiero is absolutely crazy when you really look at it.

As far as the camshaft goes I’m getting started early on research, camshafts are far from my specialty and I will need to do a lot of homework before I can speak with any authority, but yes I will be looking to only slightly modify the cam specs to match the dynamics of my engine.
After comparing many NA vs Turbo cams for the same engine I find that the statement “its hard to beat the stock cam in a street turbo engine” not to be the case when looking at OEM engines.
My cams are definitely going to see a grinding stone before I am finished with this engine, but I have a long way to go before I cross that bridge.

Thanks for your input.

Valve size and runner area have different effects on naturally aspirated vs, forced induction engines. I've never heard of a forced induction engine suffering from excessive valve size and runner volume. I've heard of it and experienced it on a naturally aspirated engine and it is solely the effect of air being sucked into the cylinder vs. air being blown in. Although I'm sure there are limitations, I would expect them to be much harder to reach with forced induction since after a larger valve install with all else being the same, your boost pressure dropping from 7 psi to 5 psi means more air entered the cylinder under the same valve timing which means more power due to less restriction and increased flow.

A naturally aspirated engine on the other hand needs the extra attention to detail because it is depending more on scavenging (an amazing phenomena) which will be less effective if the intake side of the airway becomes to volumous. It's sort of the same principle behind increasing the compression ratio, generally when you do that, the vacuum pressure goes up resulting in increased suction force which brings more air into the cylinder for compression. Likewise when you move compression in the opposite direction you get the opposite effect, sluggish air flow.

In the case of the blown engine, you have much more cylinder pressure than the typical naturally aspirated engine and generally the greater the gas pressure the greater the time it will take to expel it. The engine will likely respond better to a larger exhaust valve under boost than a larger intake valve depending on what you are starting with. Just remember pushing air as opposed to pulling air results in entirely different dynamics. Consider a combination of valve size and timing together for a balance when both will be involved in cylinder head performance. The DOHC motors already have great flow character so focusing on getting valves open as fast as possible would probably offer the greatest benefit to torque increase.

After speaking with Bruce Crower at Crower cams about camshaft trends on turbo motors I need to correct the Mitsubishi numbers I posted. I listed the IVO as later and it should be sooner so here is the correction.

Here are some numbers for Mitsubishi eclipse 2.0 DOHC NA stock cam and a mild Turbo cam.

NA IVO -14 ATDC = The valve opens -14 ATDC
TC IVO -8 ATDC = The Turbo cam opens earlier by 6 degrees (sooner)

NA EVO 26 BBDC = The valve opens 26 degrees BBDC
TC EVO 40 BBDC = The valve opens before the NA cam by 14 degrees (sooner)

NA IVC 18 ABDC = The valve closes 18 degrees ABDC
TC IVC 32 ABDC = The valve closes later the NA cam by 14 degrees (Later)

NA EVC -22 BTDC = The valve closes -22 degrees BTDC
TC EVC -16 BTDC = The valve closes before the NA cam by 7 degrees (sooner)
Ford ZETEC ZX3 DOHC NA
IVO 0.0 BTDC
IVC 32 ABDC
EVO 40 BBDC
EVC -9 BTDC

LSA 114
Duration 208/208

Ford ZETEC ZX3 DOHC Street Turbo
IVO 3 BTDC
IVC 43 ABDC
EVO 49 BBDC
EVC -7 BTDC

LSA 114
Duration 226/222

NA IVO 0.0 BTDC
TC IVO 3 BTDC

The intake valve opens slightly earlier on the TC cam (sooner)
NA EVO 40 BBDC
TC EVO 49 BBDC

The exhaust valve opens earlier on the TC cam (sooner)

NA IVC 32 ABDC
TC IVC 43 ABDC

The intake valve closes later on the TC cam (later)

NA EVC -9 BTDC
TC EVC -7 BTDC

The exhaust valve closes slightly sooner on the TC cam (sooner)

Again we see both the intake and exhaust valves opening earlier and the Intake valve closing later and the exhaust closing sooner on the turbo cam compared to the NA cam.

These numbers confirm what Bruce told me “generally intake and exhaust valves open earlier, the exhaust valve closes earlier as well and the intake valve closes later in a street oriented turbo”

He also stated that in almost all Turbo vs NA cams for the same engine the turbo will have a larger duration number to account for the extra power brought on by the turbo.

So here is what I have so far for turbo cams…

IVO Open earlier on TC applications
EVO Open earlier on TC applications
IVC Close later on TC applications
EVC Close earlier on TC applications

Duration will increase on a TC engine vs a NA one

A lot more homework to do on this but I am making some progress on the mysteries of the turbo grind camshaft.

What I am finding is that most of what you read on line about turbo cams is pure BS, it seems there are a lot of people posting on what is best for a turbo grind cam, but when these statements are put to the test with some hard numbers most of them fall to the wayside.

More to come

I've been meaning to mention how difficult to overwhelming it is to follow the numbers you've posted and then try to form an image of the effects on engine performance. Here is an illustration to put what I've been suggesting in perspective, using Desktop Dyno dotted line represents the current unmodified engine:

My base simulation at 2000 rpm for my current cam spec at 0 deg cam advance (the cam is actually fully advanced at the moment so the actual output is much less than what the graph suggests which is why I've stated to those interested in a 3900 swap, that degreeing the cam in would provide appreciable performance) is 109 hp and 286 lb/ft with 7.5 psi of boost.

Regrinding the camshaft for a more aggressive lobe opening rate, oem 2 to performance 3, all else the same provides the following effect: Increased bottom end torque, reduced top end hp. 118hp, 310lb/ft @ 2K.




Increasing duration from 216.6/212.9 to 220/225 recovers a good bit of the top end but slightly reduces the previous bottom end numbers. 116hp, 303lb/ft @ 2K.




Increasing compression from 9.8:1 to 11:1 pretty much recovers the previous loss and adds a good bit to the previous bottom end numbers. 120hp, 315lb/ft @ 2K. Since my engine has VVT, if I degree the cam in at 6 degrees advance the baseline goes to 122hp and 320 lb/ft, the cam can then be retarded to 0 degrees at about 3500 rpm restoring the peak performance providing the optimum bottom end and top end benefit the cam is capable of.



When the intended stroke increase from the offset crankshaft grind I have planned for my build is incorporated, the baseline jumps to 128hp and 335 lb/ft @ 2000 rpm and a peak output of 458hp and 399 lb/ft at 7.5 psi with the cam restored to 0 degrees advance. The unboosted simulation of my reground camshaft showed 248 hp and 268 lb/ft at 0 degrees advance. This is ofcourse a simulation although reasonable when compared to the stock numbers and the fact GM produced a 270hp, 258 lb/ft version of the engine I'm using.

Most important is that there really is no such thing as a turbo camshaft when you take the science to a technical level. There is an optimal camshaft for your engine based on the modifications you build it with. It's a balance where you try to improve on performance and keep sacrifices at a minimum, for example increasing duration for peak performance and then compression ratio to get the bottom end you loss back at the same time.

[This message has been edited by Joseph Upson (edited 12-10-2009).]

If one takes the cam specs from 20 engines one group of 10 will be NA and the other group Turbo charged, both the exact same engine configuration and compare the numbers, he should get some base line numbers.

For example if all 10 Turbo engines intake valves open sooner this would be a trend that all 10 engines share.

Convert the EVO degrees into percentages and find out on average how much sooner the valves open on the TC engine.

Let’s say that the 10 TC engines open their valves 4 – 8% sooner than on the 10 NA motors, then I should be able to apply a safe value of 6% increase to my NA cam EVO value for my engine.

This is the general idea, what I expect to find are trends, for example I have seen no NA engine that opens its intake valves sooner than the same engine with a turbo.
I also expect that the other valve events will fall into a trend as well, if I can recognize the trends and quantify them as percentages I can apply those increased or decreased values to my NA cam specs and come up with a grind that should work very well for my engine.

What you see above for the EVO math is simply figuring out how much sooner the TC valve opens compared to the NA engine as a percentage, in the example we that the valve opens about 4% sooner on the TC engine.

I hope this helps

After much research, knocking on doors and some phone jockeying I have come up with the following specs for my 3.7 DOHC stroker motor dream cams, now I need to put them to the test some how.
I also need to figure out whether or not I will need to remove material from the cams to get these specs or remove material or both. I also need to see if the 94/94 cams give me a little more material to work with as far as the grind goes.

Dream Team Specs
220 / 210 Duration
425 / 425 Lift
LSA 113
IVO -7 ATDC
IVC 39 ABDC
EVO 39 BBDC
EVC -7 BTDC

Stock 96/97 3.4 DOHC specs
205.8 / 211.9 Duration
369 / 369
LSA 110
IVO -7.1
EVO 36
IVC 32.9 LONGER
EVC -4

I also now understand why if I use a taller lifter or shim I will need a taller valve now… to bring the valve train geometry back in line. You should not raise one side without raising the other side an equal amount.

quote Originally posted by Scoobysruvenge: This may sound crazy but what I am shooting for here is not a high RPM screamer but something that pulls more like a truck (a really fast truck) right off the bottom with a nice fat torque curve

That would be the description of a supercharged engine. :-)

------------------
Steve AT 88GTP DOT com
88 GT\3800 SC\4T65E-HD

[This message has been edited by Steve25 (edited 12-11-2009).]