What would you do to build a 3.0L Race motor?

[A Quiet Boom]

On second thought just get one of those engines in Noah's sig LOL

[cstreit]

So just to give you guys an idea what I'm up against overall. Most of these guys aren't in my sub-class, but I still want to have a fighting chance...

[jluetjen]

I still want to have a fighting chance...

Oh. Let's see -- 3 liters, <$5000. Have you considered a hidden bottle of nitrous-oxide????

Chris, That is an awesome picture. There is something very poetic about the lone Porsche amongst all the iron.

[emcon5]

Chris, from the class list, and that picture, is it safe to guess you won your class that race?

Tom

[Wayne 962]

Wait a sec, Noah, what happened to your rust-mobile SC? And your Euro Carrera motor?

JE pistons are excellent, however, you still probably need new cylinders...

-Wayne

[Brad Roberts]

Great thread.

I run a 245hp 3.0 with 46's, GE80 cams, Aase springs, and stock Euro Mahle P+C's. The engine has 10.5:1 compression and will NOT run on anything less than the crappy 91 we get here in NorCal. MSD with a blaster coil. We dyno'd the engine at Woods and feel this is a very strong combination that is just barely streetable. It has very little bottom end torque and sucks gas even just running around town. We have thoroughly spanked this engine with 6 hour track marathons between 4 drivers over the last 3 years. Its bullet proof.

Now.

We have over 12k in this mostly stock engine assembled by us.

B

[cstreit]

What did it dyno at Brad?


Oh and Tom, yes, I did win the class, hard to believe eh? (THere was one other Porsche, hadn't rounded the corner...

So while that's not particularly impressive, I did set two class records at Road America, once at qualifying, once during the race...

[Brad Roberts]

Umm. 245hp. Woods jetted and tuned it. Our machine shops are a little higher priced than most, but nothing out of the ordinary for 911 prices. We had the oiling mods done, bigger squirters in the case, new valves/springs/keepers (mild port work) boat tailed the mains and knife edged the crank.

B

[cstreit]

Brad,

I keep hearing about 275-300hp being acheivable... Wondernig where that all comes from... Is it the intake and head flowing?

Did you upgrade the rod bolts along wiht the springs to get higher RPM?

[Brad Roberts]

First let me apologize for the 12K price tag. That was the complete cost of the engine (core engine for 4500$ complete)

The engine has raceware head studs and ARP rod bolts.

The motor spins 7200 RPM (MSD is chipped to stop here)

You will NOT get 300hp from a 3.0 without having a full race engine on your hands that needs to have rocker arms replaced every 4-5 races and sips 114 for breakfast.

300 is achievable and most of it is done through headwork.

The only people I know getting this HP have full Motec injection/crank triggered ignition/and 48mm TWM's.

The latest combo for us dyno'd at 327hp out of a short stroke 3.2 with JE pistons/50mm TWM's/Motec/Carrilo rods/raceware/crank triggered/twin plugged. It took 8200 RPM and 11.9:1 compression. I feel it could have been more HP with more compression, but it we lost some compression when we went with a fatter safety margin on the valve to head clearance (40thou versus 20thou)

Somebody above my post mentioned the short stroke 3.0 combo. This is the hot ticket for classes that dont care about bore and stroke combo's (we race SCCA and cant play with rod ratios and the such)

B

[beepbeep]

Cheapest way as far as i can see it is rebuildning your existing engine with new dual-plugged heads,11:1 C/R and titanium springs. Forget carburators. Go for fully mappable EFI/ direct-fire ignition. SDS-system can be done for <1300$. It will give you MPG, efficiency and better margins...something Webers never will. It's not expensive, you just need to learn some stuff...

[Brad Roberts]

beepbeep,

you say 1300$, but what about the intake setup ?? We pay close to 3000$ for 50-52MM TWM's.

I have had very good luck with the 3.2 upper intake on hot rod 3.0's. Comes with fuel rails and bolts right on (seams to flow well also).

B

[Eric Coffey]

Regarding custom EFI, another hot ticket seems to be using the `96+ Varioram intake on modified 3.0/3.2L engines. I think they run under $2000, if you can find one.


Just a side note: What's amazing to me is that the private racing teams were acheiving 350+ "reliable" HP with the 3.0L RSR's back in `75!

[cstreit]

Sorry guys, set on on the carbs.

Vintage car, can't afford a High butterfly injection, and mine have worked flawlessly for 2 years...

Fuel mileage? If I was truly worried about fuel mileage, I would buy a Honda... Seriously, I have a 27 gallon endurance fuel cell and an equal length straight exhaust.

I want the cheapest and reliable horsepower out of a 3.0L motor with 46mm webers and exhaust that I can get.

Thinking maybe I'll start out by just fixing the crappy street gear ratio's in the the 915 gearbox... Just getting out of that nasty flatspot at 4000 RPM in 3rd gear would be a big help!

[TimT]

Thinking maybe I'll start out by just fixing the crappy street gear ratio's in the the 915 gearbox...

Yeap you can find HP in your gear box, I watched one of your vids previously and kept hearing your engine dropping out of power.

you should try and catalog the gear usage at the track you most frequently run at. and probably chose a shorter 5th...... and just optimize the graphs for the rest of the gears. Then you will have to spend some time finding which ratios are available and at what cost.

I have my car geared for 138 at 7800 in fifth.. its a 2.2 but I will be able to use every gear at the track now. ad thats important instead of just having to live with the gear ratios in the stock box

[Brad Roberts]

Eric,

I'm guessing here, but I'm pretty sure those RSR's had slide valve injection. We tested a slide valve setup on a stock 3.2 and picked up almost 30hp with headers.

The really hot ticket: Porsche Motorsports has converted all the old RSR engines (3.8RSR) to slide valve. They use the plastic upper intake, remove the center section and place it on top of the slide valve setup. The center section becomes your air cleaner. At first glance you dont notice anything is different. Upon further inspection you notice there is NO throttle valve assembly on the upper intake manifold.

Cstreit,

I beleive without much trouble you can get 255hp reliably on pump gas. 300 is doable but your cost skyrockets and reliability goes down.

call Rich Walton at JWE, he will talk engines with you.

B