turbo charged 3.4 dohc....430 rwhp!

[ForcedFirebird]

Unless you are an engineer, metallurgist or connecting rod designer I don't think you are really qualified to argue connecting rod materials and manufacturing.

I don't have to be to know the limits of a motor I have been testing the limits on for several years, in which YOU obviously have NOT. You have no idea what you are talking about and posting quotes and info that is incorrect and it's getting old. If you aren't a rod designer, then you heed your own statement and resist arguing what you haven't experienced.

[TGP37]

I'm no expert but, my 3100 stock rods have held up to 8psi with occasional 12psi and a handful of 15psi runs.

I have heard and experienced, the tune means much more as a stock bottom can handle 15psi if tuned properly. But will self destruct at 8psi if not tuned well.

IMHO, what really matters is how the connecting rod is treated. I'm sure both types will fail under harsh enough conditions.

[3400-95-Modified]

So many failures are typically due to KR at high load, that is the most damaging on an engine and all your doing with forged internals is making the bottom end a bit more forgiving of a poor tune. As you guys have been saying if you get the tune right and get rid of the engine destroying KR then you can probably easily run 12-15 psi on a stock bottom end.

I run a 100 shot and have yet to blow up a piston; but everyone I tell I'm running nitrous and what shot, they ask if I did forged internals and when I say no they all cringe...

[ForcedFirebird]

So many failures are typically due to KR at high load, that is the most damaging on an engine and all your doing with forged internals is making the bottom end a bit more forgiving of a poor tune. As you guys have been saying if you get the tune right and get rid of the engine destroying KR then you can probably easily run 12-15 psi on a stock bottom end.

I run a 100 shot and have yet to blow up a piston; but everyone I tell that I'm running nitrous, and what shot they ask if I did forged internals and when I say no they all cringe...

15psi is not much for a modern engine. One of the locals here has a 99 m5 (s62 DOHC V8 ) with it's stock 11:1SCR and puts 1bar on it with a Vortech S/C and meth inter-cooling. Some of you guys remember Loner's car, that was 9:1 with FP HG's and stock 100+k mile bottom end. That was the most fun I ever had in a Corsica haha.

[timg]

The key on almost every modern engine to making it last under boost is tuning. Without good tuning, you're sunk and your engine won't last long if you go over 5-7 psi. With good tuning, many factory engines can live long lives at 10-15 psi.

I'm very cautious about meth and E85. Both are awesome for boost, but both also introduce a lot of extra complexity, expense, and potential for failure. IMO, I would do everything I can to make a setup reliable on 91/93 octane. Water/meth injection has gotten more reliable, but doing it right is tricky and costly.

Tim

[robertisaar]

E85 i can get behind.... but not as a general consumer grade fuel. or at least it makes absolutely no sense using it in a vehicle that otherwise calls for 87 octane fuel.

what does ~105 octane lead-free gasoline cost these days? if you need it, then E85 is an interesting proposition. you lose a considerable amount of range per tank, but it's probably cost-effective.

[timg]

If you're considering E85, read this first. It may make you change your mind. It's a cool fuel, but can also be a lot more dangerous and complicated than people think.

http://www.injectordynamics.com/AlcoholArticle.html

Tim

[NateD4]

Ok, which of those are you, engineer, metallurgist, connecting rod designer? Also, do you know the turbo 3.1s had forged internals from experience, or regurgitated misinformation you read somewhere? Only the rods were forged.

The OP has rods ordered so we don't need to keep discussing them in this thread.

I'm an engineer.

The information I have is from around 2000 when I first got into 60 degree engines. The turbo 3.1s did not use the 981 casting according to what I know. Though that might be the 3.4 DOHC. Its been to long to remember the exact details. I know I was looking for the forged crank for a long time and it was hard to find. Then when I read about the Gen 4 and 5 engines I decided to just get one of them instead with a forged crank. They are most likely 1053 steel though...

If anyone wants to continue talking about rods maybe a separate thread would be a good idea.

[NateD4]

I don't have to be to know the limits of a motor I have been testing the limits on for several years, in which YOU obviously have NOT. You have no idea what you are talking about and posting quotes and info that is incorrect and it's getting old. If you aren't a rod designer, then you heed your own statement and resist arguing what you haven't experienced.

What are the limits of your motor?

[NateD4]

I'm no expert but, my 3100 stock rods have held up to 8psi with occasional 12psi and a handful of 15psi runs.

I have heard and experienced, the tune means much more as a stock bottom can handle 15psi if tuned properly. But will self destruct at 8psi if not tuned well.

IMHO, what really matters is how the connecting rod is treated. I'm sure both types will fail under harsh enough conditions.

You are probably right on that. However the tune is the real question. How conservative do you tune to prevent detonation and how much power/efficiency do you need to give up to do it. Then there's also the issue of unpredictable fuel quality... To each their own...

[NateD4]

If you're considering E85, read this first. It may make you change your mind. It's a cool fuel, but can also be a lot more dangerous and complicated than people think.

http://www.injectordynamics.com/AlcoholArticle.html

Tim

Interesting read. Since I investigated the E85 option in 2008 the spec has apparently changed. Back then it was claimed to be right around 100 octane with the 15% gas content being high octane gas. Certainly a 50% mix is higher octane then straight gasoline.

One thing that I'll have to re-check is the nature of how gasoline and ethanol mix with regard to water content. Everything I can remember says that water and alcohol mix, and alcohol and gas mix, but if alcohol/gas is mixed it is very tough for the water to mix/dissolve.

If that much humidity can be absorbed by the fuel, I see no reason it wouldn't exist in the tank anyway due to condensate over night. I think perhaps the bigger problem is the fuel supply chain and getting fuel that isn't exposed to humidity while waiting for you to buy it. Once in the tank, I would hope most fuel systems are sealed tightly enough to not let humid air in the tank anyway...

This article also doesn't discuss what differences there are for vehicles with Flex Fuel capability. Does any of this matter to them? Or only in extreme cases?

[NateD4]

Forgot to mention that I know people who use car gas with ethanol in boats can have some issues due to humidity. Then again most boats I've seen have open fuel vents. Additionally the quality of cheap pump gas with ethanol is questionable as well...

[ForcedFirebird]

I know the early rods have survived 2 fuel cut detonations at full boost in my car (3.1 iron head) and after a severe detonation at 21psi in a local friend's 3.1 iron head. Both with t04e 60 trim turbos, his had a hole in the #6 piston I could stick both thumbs in, mine sounded like a cannon, then instant rod knock. How's that for testing?

[TGP37]

You are probably right on that. However the tune is the real question. How conservative do you tune to prevent detonation and how much power/efficiency do you need to give up to do it. Then there's also the issue of unpredictable fuel quality... To each their own...

Lots of logs, hours of excel and a determined mindset. I get roughly 360 ft.lb & 370 hp max at 5400 rpm pushing 11.5-11.3 in boost at 8-9psi with spark adv in the low teens........no detonation but I run 93 octane. The torque/hp readings are from the PCM. Calc'ed at +/- 3% error.

For a street performer I'm almost satisfied.....for a track racer I understand your ambition.

[3400-95-Modified]

You are probably right on that. However the tune is the real question. How conservative do you tune to prevent detonation and how much power/efficiency do you need to give up to do it. Then there's also the issue of unpredictable fuel quality... To each their own...

I don't believe in tuning a car for max power and sacrificing reliability to do so, That's just a poor method of tuning, if you want more power change the configuration to do it properly and not in that fine line of destruction.