1983 SC based race car - need more power!
 

The car is awesome, best of everything, but the engine leaves a lot on the table. 3.0 liter, standard compression ratio, standard cams, etc. Supposedly built with Pauter rods, but I haven't had it apart to verify. Induction is very trick, Jenvey ITBs, 964 plenum, Motec EFI. Exhaust is custom. The ITBs and Motec were installed and tuned by Rothsport. Runs great, but I'd like more power (who wouldn't).

Not building to any specific class, but the car was tagged NASA GTS4. According to my discussions with the seller and the good folks at Rothsport this engine made ~240 crank hp, which if my weight estimate is accurate says that in current trim this car would be at the blunt end of GTS4 class.

My thoughts are bump the compression ratio, put in some better cams, maybe displacement increase (go 98mm, 3.2). Seems a waste to toss the cylinders assuming they are still good, so the minimalist route would be simply pistons, cams, retune ECU. Maybe get a better exhaust (Rothsport guys mentioned they thought the exhaust was holding it back as is).

How high is safe to go without twin plug. Looking at Bruce Anderson's book, I see the Euro 3.2 Carrera was 10.3/1. And what cams do people recommend? With ITBs I can do pretty much anything, right?

Pics because...
http://asbury.smugmug.com/By-Land/Ra...10414592-L.jpg
http://asbury.smugmug.com/By-Land/Ra...10245190-L.jpg
http://asbury.smugmug.com/By-Land/Ra...IMG_8209-L.jpg

Supercharge it.

you may consider selling your current engine and going with a stock 3.6- you will gain another 30-50 hp and be reliable.

just a thought

Seems strange that it would have been built with Pauter rods but with standard everything else.

What do the (ever helpful) chaps at Rothsport suggest?

Of course if you went with new P&Cs you could both up the displacement and compression.

964 cams are common but given the Motec you could get something with more lift and duration without sacrificing drivability. Once you've settled on displacement & compression I'd speak to Elgin and get something custom with a custom grind.

I can’t comment on twin plugging as it’s not common in Aus (better fuel). The Motec should allow for a bit more comp though.

All this depends on your budget and what can be reused, but as I see it “stage 1” would be cams, springs, retainers and a retune. Stage 2 would be pistons for more comp, Stage 3 would be more comp and displacement. Stage 4 would be a balls out rebuild.

Whatever you decide, keep us posted!

Or better still, putting the ITBs on the 3.6. However there is no guarantee that a used 3.6 is going to be reliable.

you and I need to be friends :D

The engine wasn't updated with cams and pistons because the PO was building to the Spec 911 class.

Supercharger? hmmn. Forced induction has crossed my mind (my other car is a 930), but I am enjoying the NA experience.

My first thought was to purchase a 3.6 long lock, transfer the ITBs. Would not do stock 3.6 as there's no way I'm giving up ITB throttle response. A 3.6 core isn't cheap, and I would end up rebuilding the whole thing from the crank out. Depending on what needs doing, by my research if I take this route I need to be prepared to drop 25k (not factoring sale of current long block, I'd keep it). While I don't have a specific budget number in mind, I'd rather not put that much $ into this car.

I'm going to call rothsport and see what they recommend re: pistons and cams/exhaust. Still interested in opinions from the forum too.

Keep us posted.

THAT is the best thing you can do. :)

Jeff is very very good at this and once you give him your budget & objectives, he will tailor a package for you.

+1 Steve

We have a friend that is very fast with a short stroke 3.2L w/ 3.o case and PMOs.
But his secret is the wide body suspension and rear coil overs . . . and low weight '72 body.

Maybe spend some on engine and some on wide body . . .

Regards,

This car is pretty tricked out already on the chassis front, I don't think I have many excuses there:D

Not wide body, but some of the biggest tires you can fit under stock flares (Hoosier R6 275 in the rear 245 up front, IIRC), full coil overs (Moton 3 way adjustables), Smart Racing sway bars. Fully gutted, lexan windows all around, so only thing left on weight reduction side I can see is to replace steel with FRP parts. I could easily drop 67 lbs with hood and front fenders in FRP, after that it gets hard. That's on the to-do list at some point also.

My home track is pretty big (3.8 mile circuit) with some long straights...I'm getting crushed by the bigger hp cars on those straights.

Twin plug 3.0 with 10.5:1 JEs, PMO 50, GE 80, European 1 3/4" headers = 300 chp. Excellent race power.

Yep, call Jeff. Cams, pistons and some headwork and the rest of your package puts you north of 300. Jeff has an engine dyno. He'll give you an actual crank number before the engine ever leaves his place. And it will be tuned properly. No further fiddling.

Pelican is a DIY community, n'est pas?
 

I called Jeff. While he's happy to give his time and discuss in generalities on the phone, he's not interested in giving specific advice and selling me parts so that I can do the install. I'd have to ship my engine across the country, which is not something I'm prepared to do. Fair enough. S'pose I'm spoiled by guys like Chris Carrol of Turbokraft who was open and honest, provided excellent counsel to me as a DIY engine builder, and I bought parts from him as a way to "pay" him for his time. This isn't my first tango: http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/492267-jacobs-rebuild-thread.html

At any rate, my next trick is to call Dawes in PA. They are near to me and I figured I would call upon them for Dyno/Motec tuning assistance after I do the R&R of go fast bits.

Lindy 911, appreciate those details - that's the kind of feedback I'm looking for here.

As an aside, there is a tasty looking 3.8 RSR build for sale in the parts classifieds. One avenue would be to negotiate a purchase of that engine, then sell what I've got as is and complete. My engine is built to SPEC911 class so would be plug n play for someone who wanted to race that series. The 3.8 RSR is more power than I really envisioned, and I would need to spend some $ on my 915 to make sure it survived.

Peter's one of the best and one of the nicest guys in the business.

Pretty sure for the 3.2 a lot of people were dumping 964 cams in it all day long, not sure with the sc's though because the pistons are different (along with a few other things):eek:

Take a look at what a bunch of the POC guys supported by Aase run. There's a JE piston they all seem to run with similar cams. I'm sure if you put a similar thread in the racing forum you'd get some additional traffic.

Keep engine... Change racing format!!!!

https://www.youtube.com/watch?v=rbLD_xkLefA

There are a couple of threads on this topic on rennlist at the moment. The consensus is:

3.2 (98mm) JE pistons
964 cams
recurved dizzy if running CIS (or retune in your case)
SSI headers
twin-plug if comp more than 9.8 in the US


Which cams would work best on a 3,2 SC with 46 PMOs ? - Rennlist Discussion Forums
Upgrading 3.0 into 3.2 - Rennlist Discussion Forums

Peter, Trevor and Kevin Dawe will be able to do alot with what you're starting with
You won't find a better group anywhere

Words from a man with both humility and skill beyond his years...

^ entertaining video. Looks like fun, but I don't think we do that here in the USA. Closest thing might be a hill climb?

Call into Dawes, left a message. I know they are supporting a PCA race this weekend at Monticello Motor Club, so they probably are a bit busy with preparations.

The goal...minimum, I want to be able to keep up with the fleet of race prepped Caymans on the straights. I had to work very hard to pass this guy on the brakes. Not possible to pull away at corner exit, and for the better driven Caymans, they put such distance on me during the straights I can't make it up in the tighter bits. If I can get a bit more power I think this car will be reasonably competitive in this field and I may be able to show a few more Caymans the rear end of an obsolete air-cooled car:) I also want to get my hands into another engine. I really enjoyed the build on my 930, itching for a good winter project.
http://asbury.smugmug.com/By-Land/Ra...IMG_6892-L.jpg

We do here in the states...I have been racing with rally america since 2003 and also building a '81 SC for the task...


Home | Rally America
NASA Rally Sport

Awesome video. I get sympathy pains for that poor gearbox. Motor sounds perfect though… thank god for dry sump oiling. LOL

Getting into it now
 

Well...if this car's engine was built for Spec911 - it looks to me like it was a 'cheater' engine.

Cams do not appear to be stock SC - they are stamped Elgin "Super SC" - my research tells me these should be SC330 cams.

Pistons don't appear to be stock CIS parts either - any ideas what I'm looking at here:
http://asbury.smugmug.com/By-Land/Ra...19300934-L.jpg
http://asbury.smugmug.com/By-Land/Ra...19301282-L.jpg

I don't think these are CIS pistons.

Leakdown test prior to the tear down had some marginal numbers. I will measure everything and see how it looks, then make some decisions. I still think I can go for some bigger cams, pistons appear to already be higher compression than stock, but how high? I'll get the heads refurbed, twin plugged, and ported.

The rockers appear to be showing strange wear:
http://asbury.smugmug.com/By-Land/Ra...19300190-L.jpg

As for exhaust...anybody ever seen a set up like this one:
http://asbury.smugmug.com/By-Land/Ra...19295553-L.jpg
http://asbury.smugmug.com/By-Land/Ra...19294773-L.jpg
The headers are stepped design. Start at 1 1/2" and increase to 1 5/8"
This set up might be a weak link...and its showing some bad cracks. Last season an entire section blew apart and I had it repaired just to keep things rolling.

I would agree that looks like a cheater engine if it was indeed run in SP911. Definitely not CIS pistons for a stock engine. The deep valve reliefs give that away. I would be those pistons are 9.8:1 compression since the engine is single plug. So they're really not "high" compression. I think the deep valve reliefs can mislead us into thinking they're higher compression than they really are.

Cam followers may show some uneven wear due to using original worn-in rockers against new SC330 cams?

Those headers may have some cracks in them, but they're definitely not a weak link in the engine system. That's the Cox header layout and is a very good equal length system

http://forums.pelicanparts.com/porsche-autocross-track-racing/606654-supplier-merged-2-1-race-exhaust.html#post6002631

Those short-tube, stepped headers are optimized for an RPM range that this engine may not see, using SC330 or Super SC cams. Not an effective "marriage". :)

George's headers would be more appropriate since they have longer primaries.

^ so I've got the Cox system...thanks for that info, very helpful. The headers themselves are solid, its the merge collector and 2 into 1 muffler assembly that is cracked and failing. The cracks are quite bad where the bracket that bolts to the engine carrier is welded on to the pipes. I could have it repaired (already had a section replaced last summer that had literally blown to pieces. The material in that section is very thin wall and not the highest quality stainless.

Steve, I am not staying with Super SC cams. I want something bigger to go with higher comp pistons (and I have ITBs, so I can run just about anything). This engine rarely goes below 4k rpm on the track....spends most of its time between 4.5 and 6.5. I try to shift by 7k. Does that info change your assessment of this system or would you still recommend Georges?

This is a great injection, but you can't expect much gain over the stock 180hp with good injection. like 15hp or 20hp maybe. But the 3.0 small port head are not what you want. Best thing to do is buy one of my engine kits, GT3 crank 76.4 mm 98mm Piston and cyl kit some 3.2 heads and special cams for the injection and have yourself a 350hp 3.5 or put the injection on a better motor like a 3.6. both Jeff and Peter are great but this is not brain surgery its about as simple as a stock build.
Hopefully this helps William Knight

The ITB's will not work as well as what you have. COX exhaust is pretty good wouldn't change it. William Knight

Hi William - of course my plan is to have heads ported while they are in the shop for rebuild and twin plug machining. Your engine kit sounds interesting, but probably outside of my current budget.

http://asbury.smugmug.com/By-Land/Ra...10414592-L.jpg

http://asbury.smugmug.com/By-Land/Ra...20253054-L.jpg

Jacob,
Please don't let someone try and hand port the heads, Just switch to a better head, a real CNC custom port job is $1500, its cheeper to just get 3.2 heads and sell those for $500. Your motor needs displacement and cams I sell the Elgin cam designed for that injection. but you need to look at it this way you can put a 964 or GT3 crank in it sell the 3.0 crank, just use a good 95mm Mahle custom piston and you will have a 3.3 that goes from 200hp present to 340 hp and not out lots of money. I am just trying to help you but please don't think I am going to port and add like a 993 super sport grind and be happy because you are going to be very disappointed.

this is interesting
 

Further disassembly has revealed that the pistons are JEs. So I took some measurements last night. I will re measure to verify the findings, but it actually looks like the dome volume on these pistons are in line with 10.5:1 compression ratio. This engine was single plug...no signs of detonation that I can see. I have to go back and look at the ECU and see what kind of ignition timing this thing was set for. Seems like an odd combo of parts thus far - great ITB induction, Motec EFI, "Super SC" CIS cams, single plug and 10.5:1 piston.

Rods are Pauter, which is nice.

Nice find on the pistons. Those look like JE's version of the Max Moritz wedge/asymmetric piston with deeper valve reliefs to account for the increased dome volume/higher compression. Do the pistons have a JE part number on them? Usually it's under the pin boss, not the cast-in numbers under the crown.

Get the pistons cleaned of carbon buildup to check for detonation. It looks like this

http://forums.pelicanparts.com/911-engine-rebuilding-forum/649778-3-4-mahle-98mm-9-8-cr-dual-ignition-needed.html#post6484195

Nice find on the rods too. If you want to have them reconditioned, I would strongly suggest sending them to Pauter. Brian will take care of you. Fair cost, great communication, turnaround time is good. Main reason for sending them to Pauter is they've got the pin bushings in hand, which aren't the same as typical Porsche bushings.

Who built the original cheater motor?

dang..... someone put money into that "stock" overhaul ha ha....

Supposedly the engine was built at Kelly Moss motorsports, but honestly at this point, who knows. The induction and EFI tuning was done by Rothsport. The fellow who I bought the car from never actually ran it in Spec911, so while this is a 'cheater' motor, the guy himself wasn't. But he would have been had he actually campaigned the car in the class.

The engine was supposedly "fresh" - the pistons and rods certainly look like they are fresh, and there is other evidence that case was split and resealed recently. The rockers and rocker shafts look anything but fresh...

Pistons have thus far measured up ok. I have to check cylinders, but they look fine. I am going to pull the rods and check the rod bearings. Otherwise I think this thing is going back together with the same P&Cs. From my few discussions with Rothsport, they said the engine was "leaving a lot on the table" Hopefully new cams, some headwork and twin plug and retune of ECU will wake it up nicely. It wasn't slouchy at all, just not ready to drag race against the Caymans.

Still need to decide whether to go new on the exhaust, or find someone who can competently repair the Cox system.

Also looks like the head studs are all the std. smooth/partial thread dilavar studs? I'd think about using something other than those for the rebuild. They don't show leakage from the pictures you provided but I suspect eventually you will get leakage. Awhile back the popular idea for some builders was to use all dilavar (and we're not talking best of dilavar- the all-thread style used on the 993 twin turbo) and I don't think long term results are good. My previous engine build circa 2005 revealed all 24 were smooth dilavars and it was leaking badly from the heads and cylinders. Not pure dripping sort of leaking. But lots of weeping.

Have you decided on a cam yet? Just curious what you're thinking. We've used the WebCam 120/104 with good results. You can use a cam of that type (narrower lobe separation/overlap) due to the individual throttle bodies. I suspect that the SC330 cam with wide lobe separation was holding the engine back quite a bit, given that it's a cam that is designed to add some pep to the stock engine configuration. Note how the SC330 is listed (1/2 way down the page) = 1 step up from the stock cam for a stock engine

http://www.elgincams.com/c-por2.html

New cams will make up your mind for you in terms of what to do with the rockers- recondition :D

I would guess you can get some good money for the Cox system if repaired and sold to the right buyer. You could probably get a new basic exhaust like the George's headers for "free" if you get a good price for the Cox setup

Based on conversation with John Dougherty, I'm going for a GT2 Evo profile with a tighter lobe separation than the spec (108 IIRC). He seemed to like them for my application, rev range, and compression ratio goals. Rockers and shafts are at John's for reconditioning.

So what is collective wisdom on the a Cox 2 into 1. Is that set up more suited to a motor that will be spun to higher than normal rpm?