grumpyf14d

If I plan on making big power (>550 rw) and will be using a 16v head, which block would you choose, 2.5 or 3.0?

Voith

Interesting dilemma.

Are you starting from zero?

grumpyf14d

Yes I am. I do have a 2.5 spare block but have no issue getting a 3.0 if that is the best way to go.

refresh951

Are you dry sleeving? What bore size?

grumpyf14d

Yes dry sleeving, I would like some bottom end power as this will be a full race car and need the bottom end power for most of the tracks which leads me down the 3l path I think. I will be using a stand alone and am undecided on one or two injectors per cylinder. Will be doing individual coils and sequential injection. Plan on doing ITB from Kinsler or one of our Rennlisters. Will be making my own dual plenum intake (Audi Copy). Haven't chosen a turbo yet but thinking 3582x.

Not sure on bore size but at least 104.

Trying to also decide on half fill or full fill block.

pole position

550 wheel for the track where you turn a steering wheel ? Have 30 k ready , be prepared to count engine life in hours not miles....but 2 injectors , stand alone " big power" ITB and similar statements spell this will never go beyond the dream stage .

thingo

3.0 block, can't see any reason than other than budget to use 2.5.

333pg333

I think for a track car aiming at that h/p number then I'd go with the 3lt block. Especially if you're not going to employ a deckplate. I'd definitely not knife edge the crank if you're going to stick with a stock crank. We had a catastrophic failure and everything points to the knife edged crank as being the main culprit. Not sure where you're located and what the tracks are like but we're going from a 3.1lt motor to a 2.5ltr for the time being. I'm actually hopeful that this will provide us more linear torque and increase driveability. Having gobs of torque on a race car isn't always the fastest way around a track in my opinion.

grumpyf14d

Thanks for the constructive input. Tracks in my area include all the Mid-Atlantic tracks like VIR, Road Atlanta, Summit Point and the like. Drivability is very important. Doing the Daytona Historic is a goal though.

Ski

WTFAY?

His budget is his, he bought my old track car, smoothest transaction I ever did. There is a plan with the car, so if he does go 3.0L, he will have a brand new 2.5L for sale that has less than 10 hours on it, 101mm Mahle, LR II head, MAF and such that should do 355 -370 rwhp. Sit back and relax...

Keep us updated Keith, especially when the wide body kit starts.

Tom M'Guinn

+1 that was my thought as well. The 104mm cylinders are conjoined and have a higher floor support, so less wiggling around, and some have squirters. And the 2.7 head mates up, with its bigger valves and portable ports. And the balance shafts will be a better match if you use them.

333pg333

Some pretty fast flowing tracks you mention there. I wouldn't think a ton of low down torque is crucial at most of those, but I'm only opining from Youtube videos. (Love to run at those tracks myself!)

Even though dyno charts don't give a true indication of how the motor actually performs on the track, it still gives a reasonable approximation. Our old 3.1 had a pretty decent hit of tq. The chart showed a rise from 250ft/lb to over 500ft/lb in about 700rpms. This meant we had to employ a fair bit of traction control (right foot) at times. Obviously slow speed corners are the most difficult but even medium speed corners require a bit of delicateness.

By the sound of it you have bought a good working car with a decent motor in it now. Are you going to try the car like it is before building up a monster motor? If so, you'll get a better indication of what sort of curve you want/need from the new motor.

grumpyf14d

So the plan as of right now is to: put a fuel cell in it, 12-16 point roll cage, new wiring, new dash, & fire extinguishing system. Run the car for a few events so my son can get use to driving the car, then tear it a part. I've got to go on a deployment at the end of the year for 7 months so during that time I will be building up the parts for the engine and body.

Middle of next year the new wide body kit will go on it and finally over the winter the new engine will be in it for the 2017 season and the car's 30th anniversary. Will finish it off with running the Daytona Historic 24 hours class 8. That's the goal.

333pg333

Sounds like some great goals there. Good luck on all endeavors and keep us posted along the way.

rlm328

I would go with the 3.0 L. Be aware that sleeveing can be tricky. Different material thermal expansion rates, etc. You may want to look at E85 as a fuel source as it burns cooler and heat is hard on these engines.