To be fair, comparing modified engines to stock production engines is not a good comparison. If you really want a fair comparison, how about a highly modified LLT vs a highly modified LGX or LFX? That could indicate whether the newer exhaust configuration can make as much power.
To be fair, comparing modified engines to stock production engines is not a good comparison. If you really want a fair comparison, how about a highly modified LLT vs a highly modified LGX or LFX? That could indicate whether the newer exhaust configuration can make as much power.
Unless there's a SIGNIFICANT disparity in intake port flow that can't be overcome with port work, I'd put money on a max effort LLT beating a similar LFX. The LGX might be a tougher customer.
And Porsche's 991.2 GT3 RS 4.0 engine makes 520 HP and turns 9000 RPM.
Unless there's a SIGNIFICANT disparity in intake port flow that can't be overcome with port work, I'd put money on a max effort LLT beating a similar LFX. The LGX might be a tougher customer.
And Porsche's 991.2 GT3 RS 4.0 engine makes 520 HP and turns 9000 RPM.
To your credit and the increase in knowledge for all of us, I encountered some concern with the new cylinder head design while gathering info on the Camaro5 forum yesterday. Mace is one company that offers a camshaft upgrade for the 3.6L There's a bit of good and bad experience involving them, but an apparent conclusion that some are installing the cams without a tune and expecting magic.
The concern expressed by the individual who purchased the camshafts to install in his modded LLT Camaro, was with the LFX that some already have depending on the year and that some have upgraded to in their LLT platforms. The issue surrounds exhaust scavenging and a possible degree of interference between the exhaust pulses in the consolidated cylinder head, if I understood correctly. They may work well for what they are designed for, while at the same time possibly limiting improvement beyond factory intentions.
The benefit of exhaust scavenging is undeniable, especially when it is maximized with the use of headers, through my own personal experience with it upon learning about what it was after a header install and seeing it in action at the injection air tube check valve attached to the C.A.R.B legal headers.
I mentioned this earlier, but this topic has put a different spin on it for me; GM did an awful lot to the LFX motor to get what amounts to ~11 additional hp in the Camaro, which it has to spin 400 additional rpm to get and the same torque rating although at about 400 rpm lower. Of course that's only a small part of the picture, but still, few of us if any would be happy with those results after having upgraded a motor to larger intake valves, adding .2 additional compression points, higher duration intake camshafts, and the plastic and supposedly better flowing intake plenum all of which the LFX has.
I believe the same mods on the individual port heads would go a lot further than that. When you consider the amount of money GM saved by not having to install two cast iron exhaust manifolds per motor, my thinking is that they sacrificed aftermarket performance potential and made up for it by modifying the indispensable parts for far less than the cost of the manifolds which are actually a nice flowing design.
Here is the link for anyone interested, I've read a few so the info I mentioned may not be in this particular link. Regardless, the motor is an outstanding performer in all its iterations.
The car has headers on it although they're not shown in this link. There's a track meet between him and his wife in the link, not sure what she has in her V6 stang, but he needs to get some of it.
The issue surrounds exhaust scavenging and a possible degree of interference between the exhaust pulses in the consolidated cylinder head, if I understood correctly. They may work well for what they are designed for, while at the same time possibly limiting improvement beyond factory intentions.
That's exactly my argument. Everything that headers do for performance is unavailable on the LFX/LGX.
On an even fire V6, the bank firing intervals are 240 degrees. This means that there isn't much interaction from one exhaust event to the next, EXCEPT once the cam duration starts to exceed that number, the next cylinder's blow-down event will compromise the all-important tail end of the prior cylinder's pump-down event. Also, there's no capability to do pulse tuning and very little ability to do momentum tuning, so there it is.
So I have another question. Do tuned headers improve efficiency? If so why would GM not put them on every vehicle? Aren't Cafe standards are still a big deal for car makers? Anyway, I do remember some 70s Chrysler cars that made more power with stock manifolds than with headers. Would love to see more dyno results about this.
The new integrated exhaust manifolds are largely the result of designing an engine from the get go to be more efficient with turbos.Get the turbo as close as possible to the combustion chamber to better make use of the heat and pressure there and then bolt the catylitic converter right to the turbo and you can lower cold start emisions. New turbo v8's from BMW, Mercedes and some others use 2 small turbos where the intake used to be in a conventional V8-in the middle of the V. I am thinking they do not do this with V6's as there might not be enough room in the V.
------------------ 86 GT built 2.2 ecotec turbo rear SLA suspension QA1 coilovers on tube arms
Doesn't running a turbo defeat the purpose of headers? Besides, most cars are still naturally aspirated.
kinda, but kinda not, pulse tuning can make improvements in the gas signal to the turbine wheel, which results in a faster spool, the flip side, is that the added length of tubing creates more surface area for heat transfer to occur, so unless steps are taken to reduce the thermal conductivity of the pipe (wrap, coatings ect) then the gains could be less than expected. this is part of the reason I went with a log manifold for the turbo kit I am currently building, but the main part is that it is mush simpler, and easier to build, and in my case I don't think the gains would be worth the effort.
All that being said, I would be very interested in seeing back to back dyno pulls, changing only the manifolds and tune to test the performance difference between a well designed log, and a well designed header on a turbo car.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Originally posted by ericjon262: All that being said, I would be very interested in seeing back to back dyno pulls, changing only the manifolds and tune to test the performance difference between a well designed log, and a well designed header on a turbo car.
The new integrated exhaust manifolds are largely the result of designing an engine from the get go to be more efficient with turbos.Get the turbo as close as possible to the combustion chamber to better make use of the heat and pressure there and then bolt the catylitic converter right to the turbo and you can lower cold start emisions. New turbo v8's from BMW, Mercedes and some others use 2 small turbos where the intake used to be in a conventional V8-in the middle of the V. I am thinking they do not do this with V6's as there might not be enough room in the V.
And on the non-turbo versions, they can bolt the catalyst straight to the head. Combustion efficiency in modern engines is >99%. That is, >99% of fuel introduced into the chamber is burned. It's now essentially impossible to reduce unburned hydrocarbons by improving combustion efficiency. Thus the focus for emissions reduction is on quickening catalyst lightoff. Seconds count in that area.
quote
Originally posted by ericjon262:
kinda, but kinda not, pulse tuning can make improvements in the gas signal to the turbine wheel, which results in a faster spool, the flip side, is that the added length of tubing creates more surface area for heat transfer to occur, so unless steps are taken to reduce the thermal conductivity of the pipe (wrap, coatings ect) then the gains could be less than expected. this is part of the reason I went with a log manifold for the turbo kit I am currently building, but the main part is that it is mush simpler, and easier to build, and in my case I don't think the gains would be worth the effort.
All that being said, I would be very interested in seeing back to back dyno pulls, changing only the manifolds and tune to test the performance difference between a well designed log, and a well designed header on a turbo car.
A well designed header won't fit in the same space as a well designed log, so things can only be so comparable. Headers in turbo race cars trade pressure at the exhaust valve for velocity at the turbine inducer for very efficient transfer of angular momentum to the turbine while keeping exhaust back pressure minimal. This is key to operating the turbo beyond crossover, but it does not package well.
[This message has been edited by Will (edited 03-05-2020).]
Interesting that they put in a plug for Holley EFI, then use a manual boost controller. What kind of knuckle dragger shenanigans is that? They might as well have put a Q-Jet on it.
Interesting that they *almost* achieved crossover at the control point, even on a fairly primitive "race" system and a low boost pressure. 180 degree collectors would have done even better.
The "race" system DID hit crossover briefly in the mid-range RPM, where it hit 12 psi boost with 11.5 psi of back pressure @ 4800 RPM.
I'd like to see the difference on an even fire V6 with equal length runners, I think the difference might even favor a well designed log in some aspects. as far as packaging goes, I think both could be done on my car, in the allotted space, but I'm not going to do something that involved yet, I have too many other irons in the fire.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
I went to a local industrial bolt place and bought exactly what I needed. They did have to special order them, but they had them delivered directly to me.
I believe the torsion bar I used was from a 1989 Isuzu Trooper and was 1.1 inches, but I am just going by memory. I'll go measure it when I get time and get back to you with the specs.
Your rear bar works out to 291.2 lbs/in, which is a lot when you consider that it is also the wheel rate (connected directly to the struts). The stock 88 GT rear bar that also attached directly to the rear struts works out to 92.4 lbs/in. You have effectively tripled your rear sway bar wheel rate.
You'll either need to attach it to the rear control arms instead to substantially reduce the wheel rate or get a rather large front sway bar to balance it.
I would have to do some measuring but I think my 1.25" rear bar has a much lower wheel rate because of where it attaches to the lower control arms ('85 rear suspension). One of the upgrades that I'll be doing is to convert to the strut mounted links and make my rear sway bar adjustable. I'll be aiming for about the same range as my present rear bar.
My Herb Adams rear bar is pretty heavy and non-adjustable.
[This message has been edited by mender (edited 04-10-2020).]
Mender, you are obviously more informed than I am about this issue. My 88 did not have a sway bar from the factory. What would you expect the addition of my sway bar to be? What should I expect if no other suspension changes are made?
The result will be massive oversteer. You'll spend as much time looking through the side windows as you do the windshield.
I hate to say this, but my advice is to unhook it at the very least for now. You'll need quite a big front bar to balance that one, and I doubt there's one available. Best would be to find either stock GT bars or a matched aftermarket set and install those, then play with springs.
Just went to my shop and measured things, your rear sway bar is equal to a 1.35" rear sway bar on an '84-'87 rear suspension. That's huge, considering the Herb Adams rear bar is 1.25".
Your rear bar is just under 300 lbs/in, putting it close to the top of his performance bar and the bottom of his competition bar. Looks like his performance front bar would work with your rear bar. Not cheap though and he quit making them 5 years ago. Still might be worth a check.
[This message has been edited by mender (edited 04-10-2020).]
A rear bar that has a centre section that is 0.75" in diameter but otherwise is the same as what you have will match the rate of the stock '88 GT rear bar.
[This message has been edited by mender (edited 04-11-2020).]
I might have "found" the issue you missed. The decklid spring; when you close the deck lid, will the following interfere with the valve cover?
I was comparing your setup to my current. I bought some mounts from linsells and they seem to position the motor about an inch FWD from where yours is sitting, Which is why I started looking at clearances...
Yes, the spring was close. It didn't actually touch, but it was close enough for me to decide to make a change. Considering a gas tube lift setup. I'll see what I can come up with when I get back to work on the car. Building a SheShed for my wife right now.
Yes, the spring was close. It didn't actually touch, but it was close enough for me to decide to make a change. Considering a gas tube lift setup. I'll see what I can come up with when I get back to work on the car. Building a SheShed for my wife right now.
Good deal! I took that one off. I *might* take both off, but thinking that through. I'm catching up to you though... decided to replace the timing chain just to be on the safe side.
Should be getting my other cradle and suspension pieces back from blasting later this week. With any luck, I'll be doing a test fit this weekend.
Good deal! I took that one off. I *might* take both off, but thinking that through. I'm catching up to you though... decided to replace the timing chain just to be on the safe side.
Cool. They went with a two stage timing drive like the Northstar, but because the engine has split crank throws, the bank offset is much larger than the Northstar's allowing the one-in-front/one-behind relationship of the secondary chains to the primary chains.
It's also pretty wild how intricate the front cover casting for that engine is.
[This message has been edited by Will (edited 05-05-2020).]
I just watched a show on Prime called Enginemasters. They were doing power comparisons to test some engine mods. They severely dented headers to see what it did to the power. End result, it didn't matter. Earlier in this thread we discussed exhausts. I thought it was interesting to see the comparison.
