compatible with the stock crank journals...for the rod length to stroke ratio of 1.75:1 Stock 3.4 pistons go to below the deck and are dished. I'm using TDC 3.4 pistons and those are domed and don't hit the valves even using the 3.4 (thinner vs. 3400) gasket. I believe max lift using 2.8 style flat top pistons is .510" ... my current lift is .438" ... a .100" longer rod means I have to reduce .028" somewhere to be safe and the 3400 should cover that...
I want to bore my next block to 94mm (3.7") and be a 3.5L block with a perfect 1.75:1 ratio. My hope is the extra length lessens the need for 100 octane gas.
[This message has been edited by lou_dias (edited 01-21-2013).]
compatible with the stock crank journals...for the rod length to stroke ratio of 1.75:1 Stock 3.4 pistons go to below the deck and are dished. I'm using TDC 3.4 pistons and those are domed and don't hit the valves even using the 3.4 (thinner vs. 3400) gasket. I believe max lift using 2.8 style flat top pistons is .510" ... my current lift is .438" ... a .100" longer rod means I have to reduce .028" somewhere to be safe and the 3400 should cover that...
I want to bore my next block to 94mm (3.7") and be a 3.5L block with a perfect 1.75:1 ratio. My hope is the extra length lessens the need for 100 octane gas.
I'm not quite clear on what you're planning but it sounds like you're addressing the compression with a rod length change, without trying to guess otherwise, if that's the case I think you'll do better trying to avoid high octane by manipulating the cam LSA or duration, or both. Whatever the case you've got a plan.
and a custom set of forged pistons. The 6" rod and 84mm stroke should leave *JUST* enough room for a workable compression height (1.165 with stock 8.818 deck).
Because if bumping the rod ratio up a little bit should help, bumping it up more should just be awesome...
Interesting that GM bored the aluminum block to 92mm with a 3.307" stroke. They advertise(d) a limit of just about an .080 bore over a 2.8/3.1 bore and max stroke 3.20": http://www.gmpartsdirect.co....jhtmlCATID=175.html
Is that block even still available? It's strong enough for over 700 HP turbocharged. You won't miss the odd mm of bore size at that point.
Also, it could be sleeved for a larger bore. The technology is there to sleeve an aluminum bore block at 94mm on a 98mm bore center and have it strong enough to handle 18 psi of boost. http://forums.bimmerforums....thread.php?t=1660617
I don't know if the aluminum block is still available but in one of the catalogs, I was noticing GEN2 (Aluminum) heads look alot like GEN1 (Iron) heads. The exhaust ports look the same. Difference is mostly the intake ports where they meet the lower intake. Hey, I'll switch to aluminum GEN2 heads if it's simple...fabbing an upper intake similar to Trueleo shouldn't be too hard...
I need to sell my 4.9 5 speed before I start building another motor. I can probably get a Gen2 motor around here to source the heads and lower intake. I'd still keep the 3400 block.
I don't know if the aluminum block is still available but in one of the catalogs, I was noticing GEN2 (Aluminum) heads look alot like GEN1 (Iron) heads. The exhaust ports look the same. Difference is mostly the intake ports where they meet the lower intake. Hey, I'll switch to aluminum GEN2 heads if it's simple...fabbing an upper intake similar to Trueleo shouldn't be too hard...
I need to sell my 4.9 5 speed before I start building another motor. I can probably get a Gen2 motor around here to source the heads and lower intake. I'd still keep the 3400 block.
Don't do that... the Gen II intake is a mess.
If you want aluminum heads, go at least to the late Gen III heads from a 3500. Heck, even use the non-VVT 3500 block, since it has a 94mm bore from the factory.
However, the VVT 3500's have 99mm bores and 76mm stroke...
I don't know about that, but the LIM and UIM for the Gen II heads is asymmetric... The Gen II plenum is offset toward the rear bank. That means that the forward bank and rear bank runners in the LIM are different lengths. They are different lengths in the UIM also, but the differences are opposite, so that the assembly of LIM + UIM has the same length runners for all cylinders.
Just go with the Gen III/IV heads/intake... they are proven performers
Just tell me what you want to see. I have the upper,lower and heads from a tgp. Also have the tgp shortblock on the stand,currently prepping genIII heads for it. Also have a big journal non-vvt 3500 complete except upper manifold.
This is the genII tgp heads and a genIII 3400 head. The genII's are fresh from blaster and have been ported,genIII head has been coated but are not ported. I'll post up the lower for you in a few,it needs cleaned up as it has been acid ported and i've yet to blast it off.
Thanks! I'll have to compare the intake ports to the GEN1's I have in my basement. I don't see a different in the exhaust ports...I had my GEN1 exhaust ports ported to 1 3/16" looks like your ported GEN2 heads are ported close to that. As for the intake, the splayed valves required the change of the shape, on the GEN3, it just looks like GM opened them up a bit mor then machined in the D port shap for some extra volume. I'm suprised they didn't just keep them round and port them bigger. If you look at PAGE 1 of this thread you'll see the porting I had done. After I pulled the heads once more, I had additional polishing done.
So other than the combustion chamber re-design...allowing for 1.76" intake valves, I don't see the big deal... I'm sure the heart-shaped chamber helps with the flamewall front but I do have my spark plugs indexed (facing the exhaust valve) so meh. I still say the roller cam and it's inherent reduced frictional losses is the single biggest factor in the difference in performance. The second being the higher compression ratios of the aluminum head motors. 3rd would be the freer flowing intake. I don't think when ported properly and polished that the heads themselves differ much in flow and that the differences are more to accomodate the intakes other than the change required by the splayed heads.
That said, I'd still love to save the weight. Do you have weights for those heads?
I believe Falconer ported iron heads got rid of that "fin" on the intake port by I instructed my machinist to just polish it. Other than that, I'd say he removed as much material as the Falconer iron heads... Even my machinist knew better based on experience he had with other engines/heads (about the fin).
[This message has been edited by lou_dias (edited 01-23-2013).]
I don't think when ported properly and polished that the heads themselves differ much in flow and that the differences are more to accomodate the intakes other than the change required by the splayed heads.
What makes you think that? I think that flow numbers and dyno sheets say otherwise.
IIRC, bare aluminum heads are 13# each, bare iron heads are 26# each... right at 2x the weight. That makes ~25 lbs of overall weight savings available.
Originally posted by Will: What makes you think that? I think that flow numbers and dyno sheets say otherwise.
IIRC, bare aluminum heads are 13# each, bare iron heads are 26# each... right at 2x the weight. That makes ~25 lbs of overall weight savings available.
Thanks for the weights!
What I mean is I don't think "stock" GEN3 heads are much better than properly ported GEN1 heads for power: http://www.youtube.com/watch?v=lCKRYk4YbRA 170.4 hp/193 ft/lbs thru a manual (probably F40 like me) and I did 187/249 using the stock 3400 cam with the Fiero intake...though I doubt he has a 2.5" exhaust like me... and I hope to get my car back in April and can post a proper dyno of the tuned Trueleo intake on the motor.
I will weigh the gen II and gen III heads when I get a chance. I have a set of bare 3500 heads as well,and assembled 3.4 heads. The genIII are currently set up with the break-in springs as I am using the TGP bottom end with a ceramic coated flat tappet cam. The combustions chambers are being coated and they need to be assembled,don't really wanna pull them apart again.
The D port enhances flow,if you look thru your valve and out the intake where it comes into the bowl I bet it will look similar. Most port work ignores the floor other than cleanup and reshaping is mostly to enhance the short side radius to a nice profile. That is advice from someone I trust that does it for a living. He said the ideal is if you can recreate the curve from a 4" diameter circle into the short side radius. He does have extensive experience with the superflow and engine dyno at his work testing,but not with anything other than nhra stuff.
Originally posted by Will: The Gen III heads/intake have also done 270 RWHP on a 3400... so I think the potential is far greater in the Gen III heads.
Think about what you just said... your ported iron heads are probably pretty much equivalent to as-cast Gen III heads.
I'd love to see a list of mods on the car that put down 270rwhp...got a link?
On the intake side, the angled push rods mandated the reshaped intake ports. On the exhaust side, round was good enough for GEN2 but it looks like in order to increase exhaust flow they machined in a sort of squaring off on one side since simply making ALUMINUM head exhaust ports larger wouldn't have improved flow because of the angle the air is coming out at. For iron heads, a simple larger diameter port and polish is sufficient to achieve the same effect volumetric effect in flow. In the end I think the only debate is how big an improvement the combustion chamber is that mandated the intake and exhaust port change. Properly indexed spark plugs probably minimizes that difference and to me the heart-shaped chamber would cause more of a pressure imbalance on the piston...
I will weigh the gen II and gen III heads when I get a chance. I have a set of bare 3500 heads as well,and assembled 3.4 heads. The genIII are currently set up with the break-in springs as I am using the TGP bottom end with a ceramic coated flat tappet cam. The combustions chambers are being coated and they need to be assembled,don't really wanna pull them apart again.
The D port enhances flow,if you look thru your valve and out the intake where it comes into the bowl I bet it will look similar. Most port work ignores the floor other than cleanup and reshaping is mostly to enhance the short side radius to a nice profile. That is advice from someone I trust that does it for a living. He said the ideal is if you can recreate the curve from a 4" diameter circle into the short side radius. He does have extensive experience with the superflow and engine dyno at his work testing,but not with anything other than nhra stuff.
My machinist did an amazing job. He ported and polished as deep as possible only backing off where he thought there might be a coolant passage near by. He did the heads, once I saw the heads, I had had another guy do the intake in the pics I posted. When I saw the work he did on the heads I had him go over the 3 intake pieces of the Fiero intake that I had someone else do. So the pics you see of my intake weren't polished, he touched up the porting and polished them beyond what I have in the pics. I don't have pics because my installer needed the intake on the car to finish the job and give me the whole car running. I wish I had done the DAWG neck mod, but I didn't and I think that's why I hit the 4400RPM "wall"....a problem I don't currently have with the Trueleo intake....
I don't have a specific link, but the 270 WHP build has been on the www.60degreev6.com forum for a few years now...
The canted valve, which required the angle pushrod, is what really drove the port reshape. Don't kid yourself into thinking the ports are similar. Go find some flow numbers.
Indexing the plugs will NOT make up the difference between the iron head chambers and the aluminum head chambers. Builds with 12:1 comp run on aluminum head engines... Don't kid yourself about that either.
There's no such thing as pressure imbalance on the piston... Just like 1.75 isn't a better rod ratio than any other rod ratio.
[This message has been edited by Will (edited 01-24-2013).]
I have to agree with Will on this one Lou, the small block 400 had 5.565" rods so 5.7 can't be all that bad. The 60 degree forum has flow numbers floating around on the site for some idea and I recall the D shape exhaust port in the aluminum heads serving the same purpose as the fin in the cast iron heads, to improve flow. You can also find the Superdave there, I'm not sure about his work with a 3400 but I know his 3500 was at or near 300 hp naturally aspirated and as far as I know it has a cam, and head and intake work with the stock 9.8:1 compression so there was still room for improvement above that by swapping in the flat top pistons from the 3.6 DOHC. If I find the link I'll post it here for you to review.
I have to agree with Will on this one Lou, the small block 400 had 5.565" rods so 5.7 can't be all that bad. The 60 degree forum has flow numbers floating around on the site for some idea and I recall the D shape exhaust port in the aluminum heads serving the same purpose as the fin in the cast iron heads, to improve flow. You can also find the Superdave there, I'm not sure about his work with a 3400 but I know his 3500 was at or near 300 hp naturally aspirated and as far as I know it has a cam, and head and intake work with the stock 9.8:1 compression so there was still room for improvement above that by swapping in the flat top pistons from the 3.6 DOHC. If I find the link I'll post it here for you to review.
"Not to knock the L67, but pound for pound the later 60 degree engines appear to be more efficient and powerful by design rather than fluke and I can't understand why the Fiero owners are even considering installing a naturally aspirated version of the 3800 or the 4.3L V6 in spite of that. " -I've been saying this for years...
Still it's light on actual information. :/ Again, since I'm using the 3400 roller cam block, I can use the same cam...but again - what cam?
"274 WHP and around 250 WTQ.." I've matched the torque already when I had the Fiero intake, the only reason I didn't keep making power after 4400 is because of the Fiero intake neck and the fact that Ryan tuned for 12:1 followed by an epic fail trend to 10.5:1 in the upper rpm band... Despite that, I had a nice flat torque curve until the fueling went south. I have since corrected the tuning to be 13.0:1 across the board and have switched to DIS, a '7730 running $A1, a Trueleo intak with an L98 (twin 48mm) throttle body. Please believe me when I say I am making more power than 187/249 currently. My peak is definitely ~5k rpm but I don't expect the car back until April so a dyno is a ways off. My advance at 4800 is 39 degrees.
Clutch dumps at 3000rpm still chirp the tires running 275 width street slicks on 17x10 wheels. The two times that I did 5k+ rpm dumps, I snapped axles...
[This message has been edited by lou_dias (edited 01-25-2013).]
Here you see how my ports on the Fiero intake that I used to dyno 187/249 compared to stock. This is with the intake shaved down flat with the rest of the bottom part of it.
Here you see how I compare to a 3400 intake:
What you don't see here is that while the 3400 ports look bigger, they actually aren't as big on the bend by a little bit at least on one side.
They also have a larger turn radius through the 135 degree bend than the Fiero parts do (particularly where you have the Fiero manifolds cut down... Have you checked to the sure you don't have a knife edge for the air flow to go around inside your port?)
[This message has been edited by Will (edited 01-28-2013).]
In a turn, flow is more important in the outer diameter than the inner. This is the same concept as to why the D shape improves flow on the exhaust ports. The opened up flat area would have to be on the outer diameter of airflow in a turn. My #'s don't lie and using the Fiero intake, without the "dawg" neck mod, I have posted higher #'s than any other Fiero intake-based motor, naturally aspirated of course. Like I said, my machinist was able to port and polish deeper into the flat area of the intake because he shaved it down.
Knowing what I know now about tuning myself, I would have loved to get my A/F ratio at 13.0 and also applied the "dawg" mod to see how far I could take it. There is a forum member offering to dawg-mod an intake but it's pricey. I will try to find someone to do it locally.
I still have this intake and the day my bone stock '88 formula dies, I will move this intake to that car along with another 3400/3500 bottom end. Seems pointless on a 2.8 ...
[This message has been edited by lou_dias (edited 01-28-2013).]
In a turn, flow is more important in the outer diameter than the inner. This is the same concept as to why the D shape improves flow on the exhaust ports. The opened up flat area would have to be on the outer diameter of airflow in a turn. My #'s don't lie and using the Fiero intake, without the "dawg" neck mod, I have posted higher #'s than any other Fiero intake-based motor, naturally aspirated of course. Like I said, my machinist was able to port and polish deeper into the flat area of the intake because he shaved it down.
Knowing what I know now about tuning myself, I would have loved to get my A/F ratio at 13.0 and also applied the "dawg" mod to see how far I could take it. There is a forum member offering to dawg-mod an intake but it's pricey. I will try to find someone to do it locally.
I still have this intake and the day my bone stock '88 formula dies, I will move this intake to that car along with another 3400/3500 bottom end. Seems pointless on a 2.8 ...
D-shaped exhaust ports have the flat side on the short side of the turn.
A flow separation on an edge or sharp corner on the inside surface of a turn will kill flow throughout the entire passage.
Originally posted by Will: D-shaped exhaust ports have the flat side on the short side of the turn.
A flow separation on an edge or sharp corner on the inside surface of a turn will kill flow throughout the entire passage.
Well, that's kind of fail. I have the manifolds but not the heads to look at since I sold them. I'm starting to see less and less reason as to why the heads are the improvement people think they are. The intake is obviously an improvement over the Fiero intake...
I know there's a bit more potential left in what you're doing Lou, but at this point it's about like digging for goal in an abandoned mine, you might get lucky to make the effort worth it. I'd much like to see you conform to building up a later model engine as opposed to cannibalizing it. Understand that the numbers Superdave posted were from a second dyno after some changes, the first put out a little less hp and more torque, basically a change of balance, not to mention he didn't take advantage of the opportunity to bump up the compression 1 to 2 points to take advantage of his cam which might have dragged his tq up to 300 lb/ft at the wheels also.
Here is a video of the motor idling along with his cam specs and it sounds nice. If you just don't want to deal with the aluminum heads or non stock look I understand, otherwise I think you should swap the complete 3x00 motor and let "iron side" go.
https://www.youtube.com/watch?v=XP048yTMb_8
[This message has been edited by Joseph Upson (edited 01-28-2013).]
I know there's a bit more potential left in what you're doing Lou, but at this point it's about like digging for goal in an abandoned mine, you might get lucky to make the effort worth it. I'd much like to see you conform to building up a later model engine as opposed to cannibalizing it. Understand that the numbers Superdave posted were from a second dyno after some changes, the first put out a little less hp and more torque, basically a change of balance, not to mention he didn't take advantage of the opportunity to bump up the compression 1 to 2 points to take advantage of his cam which might have dragged his tq up to 300 lb/ft at the wheels also.
Here is a video of the motor idling along with his cam specs and it sounds nice. If you just don't want to deal with the aluminum heads or non stock look I understand, otherwise I think you should swap the complete 3x00 motor and let "iron side" go.
https://www.youtube.com/watch?v=XP048yTMb_8
Dave initially had higher compression(iirc 10.9:1) but found that with the high lift of the cam, the exhaust valves were kissing the pistons. he was using graphite .040" headgaskets used on the ironhead 3.4 660.
Lou, the D shape exhaust port on later Gen III heads optimized the short side radius increasing the flow signifcantly. ports were also raised to create a more direct transition to the valve. also, the canted valve decreased shrouding as well. proof is in the pudding, a Gen III topend will build on your current setup. keep in mind that the assembled steel factory camshaft is somewhat weak and has been known to break, WOTTech has some good grinds that can be matched to your setup.
I know there's a bit more potential left in what you're doing Lou, but at this point it's about like digging for goal in an abandoned mine, you might get lucky to make the effort worth it. I'd much like to see you conform to building up a later model engine as opposed to cannibalizing it. Understand that the numbers Superdave posted were from a second dyno after some changes, the first put out a little less hp and more torque, basically a change of balance, not to mention he didn't take advantage of the opportunity to bump up the compression 1 to 2 points to take advantage of his cam which might have dragged his tq up to 300 lb/ft at the wheels also.
Here is a video of the motor idling along with his cam specs and it sounds nice. If you just don't want to deal with the aluminum heads or non stock look I understand, otherwise I think you should swap the complete 3x00 motor and let "iron side" go.
https://www.youtube.com/watch?v=XP048yTMb_8
Sounding "nice" is a matter of taste. I personally don't like the open exhaust sound. I dynoed my car the same way it drives on the street. While I had no cat, I used the Trueleo headers into 2.5" piping following the stock routing with a Flowmaster 55 series muffler and two outlets. I'm no longer using the Fiero intake other than the lower part. I don't have a current dyno but I know how much power my 1997 6speed with cat-less exhaust Corvette made, how much power my stock '88 Formula makes, my 4.9 GT 5spd(172/265) makes and how much this Fiero makes. With the Trueleo intake and my current tune, my 4.9 has no chance of being near my v6 hybrid.
Here's my 3.4 v6 doing a sub-20 second lap with a bogged launch. https://www.youtube.com/watch?v=kbaujyDgT3Y
same car now with 4.9 doing a 21 second lap with my friends mentioning my axle-snapping incident (not knowing it was my other Fiero) https://www.youtube.com/watch?v=WZbYLaI2B5U
As you can see they are about 2 seconds apart on the same track as it stands right now.
Originally posted by lou_dias: In a turn, flow is more important in the outer diameter than the inner.
This is more important in a boosted application then a N/a application, remember, the air is being pulled down, nut pushed, so it's going to go for the shortest distance possible.
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I know these lines Look crooked on paper, but I swear I've got them straight in my head.
Originally posted by ericjon262: This is more important in a boosted application then a N/a application, remember, the air is being pulled down, nut pushed, so it's going to go for the shortest distance possible.
That's a thought but is there any scientific data behind that? To me, flow is flow and it doesn't matter what's driving the pressure imbalance. I could be wrong, but I just want to see it. Thanks.
That's a thought but is there any scientific data behind that? To me, flow is flow and it doesn't matter what's driving the pressure imbalance. I could be wrong, but I just want to see it. Thanks.
You can only pull about 32" of vacuum but you can build a lot of pressure to force through a given passage. The port characteristics still have an effect but yes you'll be able to over come some flow inefficiencies with forced induction that would be more of a hindrance naturally aspirated.
Originally posted by Joseph Upson: You can only pull about 32" of vacuum but you can build a lot of pressure to force through a given passage. The port characteristics still have an effect but yes you'll be able to over come some flow inefficiencies with forced induction that would be more of a hindrance naturally aspirated.
I'm talking about flow characteristics of pulling versus pushing. To me it shouldn't change and that the outer diameter is what's "more" important. To me, you would want to square the two corners of the outer diameter of a tube to increase flow compared to the inner area. While increasing the inner area may increase overall flow, I am just questioning the efficiency of one over the other and specifically in the case of a NA motor. GM doesn't always do things for the reason you think. The shape of the intake ports on the head were mandated by the splayed valves. The pushrods would be in the way otherwise. They may have made the total area bigger over time when compared to the cast iron heads, but that is probably more because they don't sell a car with factory cast iron heads any more and hence a port and polish(bigger ports) is what would be standard today if they sold a 3X00 with cast iron heads today as the displacement increased.
[This message has been edited by lou_dias (edited 01-29-2013).]
Originally posted by Will: There is no pulling, only pushing.
Yea, was getting confused with the intake side in a boosted and non-boosted application. On the exhaust, the piston is always coming up to push the exhaust out which re-iterates my point about where GM *should* have opened up the exhaust. Too bad I sold my Gen3 heads when I did. I never really had time to inspect and compare them...
So seeing as how the 3.1 is the only motor to have all generations of heads...
Gen 1: 150 hp (iron) Gen 2: 140 hp (aluminum, but intake ports are fail) Gen 3: 170 hp (roller cam with bigger ports over gen 2)
If you ask me, Gen 1 heads flow better than Gen 2 even if the Gen1 were stock (not ported). Gen 3 was an improvement over Gen 2, but its not proven better than ported Gen 1 heads yet. We have GM flowing 275hp from a 2.8 probably with an open exhaust and we have a 3500 flowing 274 hp definitely with an open exhaust from Gen3 heads.
