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Build my own race engine?

I am a mechanically astute guy. I have the proverbial awesome set of tools. I built my '69 911S to what it is now, I have restored a number of cars including several E-type Jags from the ground up and I have rebuilt engines before (Triumph TR6 about 15 years ago). That said, I have never built a race engine or 911 engine before.

I have a complete '73 2.4 T long block that is a 7R case. I also have a complete MFI setup.

I am thinking of building my car out to a 2.8RSR replica for PCA, HSR and NASA racing. My plan would be to continue DE instructing events and such through this year. I would build the engine during this time. Then over next winter build the car out to full race spec, install the engine and go racing next year.

So, given I have this core stuff and I want a 2.8 or 2.9 (under 3.0 is good for the classes I want in each group). What should I build?

I want to assemble the engine myself. I want someone else to obviously do all the machining and to provide me all the parts and to give advice. I am really hoping Henry Schmidt will help with this.... He built my current 2.6 and it has been a very powerful engine though the oil pressure is a bit suspect.

Is it realisitic to expect to get someone else to handle getting all the machining done and to help with getting all the parts just right and specing out the engine? Can a first time Porsche builder assemble such an engine correctly?

My goal is 300hp. I definitely want MFI. I am assuming twin plugs. My budget will be something like $12K-$15K. When done I will probably go through my current 2.6 and then sell it.

What do all the guru's suggest?
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Old 03-23-2005, 02:29 PM
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I'm not even a whisker of a guru, but have picked up a few things along the way. Pistons that large in a 7R case might be too much, especially the 2.9. Even a 2.7 in a mag case was somewhat overstressed. You might consider selling the the 7R and finding a good 3.0 turbo or SC case if you want to go to the class max of 3.0L. For the power and piston sizes you are after, it's good insurance.
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Old 03-23-2005, 03:38 PM
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Forget using a T case and parts for a basis for any race engine. To many changes, to much cost to little usefull parts.

Here is a partial list of why NOT

Case is mag
rods are not shot peened, nitrated
crank is cast instead of forged
pistons are low comp and cast instead of forged
cams are way wrong
heads are wrong
oil pump is lacking
the whole darn engine is lacking.

Start with a good al case S engine as a mininum.

You will need the machine services of say Ollies. and much advise.

One big problem with Porsche is its hard to tell what to do to which case engine without paying someone to first do it for you, ie info is NOT forthcoming.
Old 03-23-2005, 08:51 PM
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I figured only the case itself would be useable. However, I thought the 7R cases from a 2.4 engine made a good place to start from. I also assumed it would need all sorts of trick machining.
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Old 03-23-2005, 09:09 PM
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The 2.4 case is a good case for up to 2.8L. BUT, if I were in your situation, with your budget, I would start with a 3.0L Turbo or Euro carrera case (1976-1977), which is aluminum and uses a 6-bolt crankshaft. Then get a 2.0L or 2.2L (1965-1971, non - 911T, either S or E) crank, some good rods (maybe pauter, otherwise nitrided 911S 2.0L or 2.2L). Use good fasteners (ARP) and use forged pistons (JE or Mahle). You can use a 95mm bore (2806cc), or you can bore out your 95mm cylinders to be 96/97/98mm (2866/2926/2987cc). A 3.0L with a 66mm crank would be an AWESOME race engine. The short stroke would make it a rev-beast. I think those around hear call that engine the 3.0SS.

The engine may be more expensive in parts than a 2.8 with a mag case, but in terms of machining, it's cheaper. The aluminum case doesn't need nearly as much work (=time) as the mag case does, plus it's stronger and better suited for racing. Look at VARA, they all use aluminum cases.

Talk to Ollie's, likely get the case shuffle-pinned, and get the crank knife-edged and balanced. Then use some 911SC heads with MFI line inlets tapped into the intake port.

You can do it all yourself, no problem.


ps. snowman, the T crank was only cast for 1970-1971.
Old 03-23-2005, 10:46 PM
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Where to get a 3.0L Turbo or Euro Carrera case? Sounds expensive. I do already own the 7R mag case. Is all the machining work more expensive than the later case?

I do have the original '69 911S engine from my car. I didnt think I was going to be using it and actually had hoped to sell it to help fund this entire thing.

My core is a '73 2.4T 7R.... is that crank no good for a 2.8 build? Can the heads be machined to specs for racing or is it better to just find SC heads?

I did figure I would need Carillo or Pauter rods and I want all ARP hardware. I figured the mag case would need line boring, spigots bored, shuffle pinned, windage mods, pump mods and racing hardware.

I am open to all suggestions. There is no hurry, I will not start gathering parts and such until summer.
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Old 03-24-2005, 06:45 AM
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The 3.0T case/Euro3.0 case is about $1200. You'll probably put about 400 into machine work~$1500. The 7R will probably need $1k in work, AT LEAST, with case-savers, line-boring perfect, oil bypass modification, decking, all that stuff...lots of time. You can sell your 2.4 case for good money. I would say the amount you'd have in each is very similar.

The 2.4 crank is fine, it's what a "regular" 2.8 would have used (w/ 92mm pistons). The 2.0 crank destrokes it, and to get 2.8L, you use 95mm Pistons instead of 92mm. Just "racier" to have a shorter stroke and bigger bore.

I believe the stud spacing is different on the 3.0T case. SC heads aren't that expensive compared to regular 2.4 heads. Maybe $400 vs. $250.
Old 03-24-2005, 10:06 AM
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Why can't mag be used for racing? Yes, old worn ones are not good but new ones are fine.
The engine is already in the wrong place so the last thing you want to do is to increase its weight.
Old 03-24-2005, 10:25 AM
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Umm.. not sure why people always complain about the 2.4T motors. They're very different than the earlier ones.

They have the same case as the E's and S's, if it's a 7R then it's the strongest of the Mag cases and what the factory used for it's 2.8's
The crank is also exactly the same.
Yes the rods aren't shot peened, but are the same as the S's save this and nitriting.
The heads are exactly the same, except for porting, which for a race motor will get ported anyway.
Same thing with the cams, it's a race motor, so cams will have to be changed one way or another

Yes the oil pump isn't the best, but good used ones can be had relatively inexpensively.


If the class you're looking at is under 3.0 liters can you run a 95x70.4 motor (SC)? The crank and case are much more robust and much easier to obtain than an early sandcast case or an early turbo/ 3.0 carrera case.


not much of a race guy, it it would seem reasonable with twin plugging on race gas to make 300 out of a 2.8. The factory 2.8RSR speced out to be about 308.
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Last edited by Tim Walsh; 03-24-2005 at 10:59 AM..
Old 03-24-2005, 10:56 AM
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minimizing weight is of course always a priority. With an under 3.0 class the target, it would seem a twin plug 2.8 with MFI based on a properly built mag case would be the ticket.

Considering I already own the case and crank required (provided the 2.4 T crank is forged and acceptable) I figured I had a leg up?

I know the P/C's and rods are junk as are the cams and hardware. I would get new P/Cs, rods, hardware, cams ect. I doubt I would want to use the crank from the 2.0 S engine since that would destroy the value of that engine? But then again the idea of a really fast revving short stroke motor is appealing!
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Old 03-24-2005, 01:30 PM
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Are there any year constraints? I don't think it would "destroy" the value of the engine to use a 2.0S crank--the rest would be modified anyway.

Bottom line; constraints of a 7R case is 92mm P/C. With a 2.0S crank, you'll only be max 2.6L, which you have. Choice then is 2.4 crank on 92mm, that is a 2.8, which is a truly fantastic engine, in my opinion. But, for racing, I think it makes more sense to use the 3.0 aluminum case, 2.0S crank and 98mm P/C. That will make a 3.0 as I said, or you can get 2.8L by using 95's. Both great engines. Henry Schmidt shows one of these 2.8L short-stroke aluminum engines putting out 315hp at 8500rpm (I would estimate a short-stroke 2987cc would be about 330hp on the same dyno, same conditions) on his website. Several builders (including Henry Schmidt) also don't trust the 2.4 crank above ~7800rpm. Frank Beck broke one hitting 8200 in a 2.7/2.8 race motor like you're planning.

Lastly: the aluminum case is heavier, yes, but only by about 20 lbs. In my opinion, having a LITTLE extra weight in the name of a lot of extra reliability is better.

JMHO. YMMV

Last edited by YTNUKLR; 03-24-2005 at 04:28 PM..
Old 03-24-2005, 04:23 PM
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