911 Turbo race motor (based on SC)
 

I have read and searched before asking!

I am building a Turbo race engine from a 3.0SC (930/09) engine and would like a little input.

The goal is some 400-450bhp, max 7000rpm, small twin setup (less lag), no silencer, big twin intercooler. Car MUST be track-able and I am not after ultimate max bhp.

No worries about space, fit or looks - it's a race car!

1) What pistons (and supplier) do you recommend. First I was going with the 3.0 option, but now somebody recommended 98mm p/c? (must then fit 3.0 crank!). JE, Mahle, Andial?

2) Is the 74.4 crank a must or can I stay with the (like new) 70.4 I have?

3) We were planing on using a 964 PLASTIC intake manifold with adapters - securely fastened. Comments?

4) I am running twin-spark, 102.6 fuel, what is your suggested max compression?

5) Would a factory 964 cam be nice in this setup?

Any more ideas? Please chirp...

Regards
Tom

Oh... any competitor looking in here - BRACE YOURSELF.

I can take a stab at two...


#2 corky bells book on turbocharging says that a longer throw crank is better for turbocharging. I cant remember why....

if you stay with the 70.4 you will have a SS 3.2 or with the 74.4 a 3.4. more displacement with a longer throw would be ideal... but 3.2 cranks are alot of $$$$

#5 I dont know if this helps... but Randy Blaylock wrote .
There was a debate about which cam profile to use, the more common ones being SC or 964, and others. SC cam profile gives better overall power than stock 930, with better low end than 964, but less overall. The application really determines the cam, and I used the car for 10% street and 90% track, so moving the power up the curve with 964 cams vs. SC cams made sense for my use.

Are you using EFI?
At what rpm would you like the turbo to spool up?

John,

Yep, EFI (Wolf 3D V4 or our local G.T.S.). I was thinking that the 964 plastic intake manifold (42 ID) with 700cc Bosch injectors would be a nice setup. I would fit a larger throttlebody with TPS (for the EFI).

I suggested the 964 cam because I have a few sets in stock (budget consideration!) and would like power btw 4000-7000rpm. Turbo 'coming in' from 3500rpm ??

Nick,

Agree on the crank $, but will I find 98mm Turbo pistons for the 70.4 crank? - ANYONE?

Tom

If by turbo pistons you mean low comp ratio\flat-top.... i think JE pistons can build you a 98mm to any spec's you want..

i called them about 95mm at 8-1 ratio for an SC (turbo)
they said they could help me out...
its worth a call at least!

Do you already have the 964 plastic intake? You need to buy adapters so they will bolt up to the 2 bolt sc heads versus the 3 bolt 964 and then later 993 heads it was designed for. A metal 3.2 intake will bolt right up and is stronger than the plastic so it can handle boost reliably. I believe it was StrohkerRacing on this board that wrapped his plastic 964 intake with kevlar to beef it up. Also the sc heads have a taller intake versus the 3.2 and later 3.6 heads so clearance in the engine bay may become a problem.

You say race engine so I would suggest the 964 cams. On your crank decision some reputable builders I have spoken with like the 3.0L rods better than the 3.2 simply because they have a larger, stronger rod bolt. You can always modify the 3.0 rods to work with a 3.2 crank but the crank is heavier than the 3.0. JE can make you pistons anyway you like them to fit any bore and rod size. Comes down to money, how you want the motor to perform and then more money.

Happy building!

The 964 cams will work, but I suspect you will outgrow them quickly.

Gents,

Thanks for the input.

I like the 964 intake manifold because it apparently is more harmonic and flows a lot more air than the 3.2 manifold. The adaptors are easy (already have a 3.0SC with the same setup).

ANDIAL have a set of P/C 98mm (935 style) that may work - that would give us 3.2. Anyone know this setup?

John Camgrinder: I have considered the 964 cam limitations, but would like to have a broad powerband btw say 3500-6500 (max 7000) - revs cost money! What other options do I have? Africa is lovely but also far from retail US!

Tom

I think 3500 to 6500 rpms is reasonable with the 964 cams.
What turbos are you using?

I bet shipping to Africa is less than $100 U.S. Postal.

John,
What's the time in CA now - aren't you meant to be sleeping?

Yep - courier is not too bad, but then customs add 20-40% duty and then the Receiver add 14% VAT. All of this on the goods AND the freight! Adding customs to freight and VAT to duty is great!

I used to ship all goods to a 'central' source in CA and from there send bulk to Darkest Africa. Unfortunately 9/11 and your state tax sort of spoiled that.

The main reason was that I have some four sets of 964 cams in stock.

I'll mail you a little later when I decide on piston/compression choice.

Thanks for all the help.

Tom

Does it have to be 3.0L for the rules? If not I would get some JE pistons and make it 3.2L with maybe 8.0 to 1 CR. I think that will give you the power that you want.

Here is a data point. I have an early 930 with stock pistons. 6.5 to 1 or so CR. I am running SC cams, shorty headers, a K27-7200 turbo, EFI and a big intercooler. I got 352 RWHP on a DynoDynamic dyno. The motor runs very strong and has a fairly low boost theshold and hardly any lag.

Here is the chart

Deanhttp://forums.pelicanparts.com/uploa...1123851905.jpg

Oh yea,

I would also post turbo questions on other sites.

http://www.c2turbo.com/forums/index.php?

http://www.turbo911.com/

Dean

Dean,

It can be a 8.0 ltr as long as it remains a 911 flat-6! I'm gunning for class AA unlimited so I need some wooma.

Your power curve is very nice and linear - a bonus to me. What do you mean by 'shorty' headers?

Is your intercooler OE?

Tom

It was kinda late. I have twins, and are out of the crib and sleeping in beds. First time last night. Its a lot of fun :)

Tom,

Shorty headers are not equal length. They are a short as possibe to get the turbo to spool faster.

Here is a pic of my intercooler. It is not OE. I built it.

I think you will have no problem meeting your goals. You could also look into GT2 Evo cams. I know some people running them and they all like the cams.

Oh yea that dyno chart was running just under 1 bar of boost.http://forums.pelicanparts.com/uploa...1123892215.jpg

Another Q.

I have a 993RS oil pump in stock. Will it fit into my 930 case?
Is this pump better than my SC pump? Worthwhile?

Dean,
That's not an intercooler - it's a family size braai (barbeque, grill...).

Does anyone sell the short header and twin-turbo setup as a bolt-on kit for a 911 race motor? Would save some time.

Thanks. Tom

Tom

I have a GT3 oil pump fitted to my early 930 case. It required clearancing of the relevant main bearing webs (I used a cutoff wheel and then a die grinder). I don't know the pump you are referring to, but it can't be larger than the GT3 pump with its extra scavange inlet. Just lay the pump in your case and you'll see where you need to whittle.

My early sandcast case accomodates a 930 turbo pump (with clearancing) with no problems.

If this pump is as long as the GT3 or 930 pumps, you will need the short splined coupling tube (I think there are only two lengths for this - long and short).

Is this RSR pump a separate part, or is it just the "964" pump?

Walt Fricke

Walt'

Hrmph... just checked the oil pump. '964.xxx.so forth'. Came out of a 993RS 3.8.

Is this pump bigger than the 930 3.3T ?

Why did you use the GT3 pump?

BTW, my car uses GT3 brakes - so I'm already in the family!

Regards, Tom

Tom

I bought a GT3 pump because it cost a bit less than the 3.3 turbo pump (the turbo pump I have in my existing, at some time to be spare, engine I got before the GT3 was made and as a good deal swap of some other parts). I think it may not cost more (or at least not much more) than the 964 pump you have.

I just rembered that you will have to clearance a 930 case to fit the 964 also. A friend had both a 964 and a turbo pump in his private stock, and we held them up side by side to see what apparent differences there were. I don't recall anything of significance in terms of the lengths of the internal gears as best one could tell from the outside.

The spiel on the 930 pump was that because it was all cast iron it changed less when hot and was better for racing than the 964. My suspicions are that the 964 pump is probably just as good, but that is just a guess. If I had one I'd probably be using it for my 2.8 project motor.

Walt Fricke

Walt
Just 'plugged' the 964 pump in. I see I have the long coupler tube - what model/engine used the shorter tube?

Otherwise I'll just shorten my tube - have a good engineer.

Thanks for all the help. Enjoy your weekend.
Tom

Tom

I'm not at home or I'd give you the part number from a catalog, PET, or by finding a receipt for one I bought. However, the 3.3 and later Turbos, plus all of the 964 based engines would have had to use the short tube.

I suppose cutting and welding would work if done right, as it has some reserve strength: The tube is stronger than the end of the intermediate shaft (at least than a 30 year old one): connecting rod bolt fails and rod cap bashes and jams oil pump, splined end of IS breaks off as if machined.

Walt

ROUND TWO
 

I can get my hands on a factory GT2 (993) twin inter-cooler at a decent price.

Do you recommend going that route or rather manufacturer our own twin intercooler? Do bear in mind that I have access to some very experienced engineering people who have in the past made some SERIOUS coolers for Porsche racing cars - BUT it is going to be way more expensive...

What kind of power will the 993 cooler 'permit' on something like a 3.0 with small twin-turbo's???

Tom

1) What pistons (and supplier) do you recommend. First I was going with the 3.0 option, but now somebody recommended 98mm p/c? (must then fit 3.0 crank!). JE, Mahle, Andial? If going with new PNC, yes increase size. 7.0 Either one of the three you mention would be fine.How about ceramic coated with dry lubed skirts.

2) Is the 74.4 crank a must or can I stay with the (like new) 70.4 I have? Stay with one you have, Either way, machine shop work required after you buy PNC.

3) We were planing on using a 964 PLASTIC intake manifold with adapters - securely fastened. Comments?
Yes or go with a 3.2 intake if have to buy one or the other

4) I am running twin-spark, 102.6 fuel, what is your suggested max compression?
7.0 . Keep boost at 1.0 bar

5) Would a factory 964 cam be nice in this setup?

Yes

6) Yes on IC shown above

What about flame ring. New rods? Twin plug/port/Flow/CC Heads High output Fuel injectors/pump

Boost and CR can be increased, but I wouldn't in order to not give up reliability at same time. What ever you decide have fun. Good luck. Be safe.

Regards,

Bernard,

Thanks alot. You bring up a new issue.

What's the take on ceramic coating on this board. Some people coat 'everything', some coat exhaust ports and piston tops only and some say leave it as Porsche did.

Bear in mind that I'll run relatively low boost, it's a track car and I have plenty air / oil cooling.

Any input on the intercooler ??? Anyone...

Tom

It makes a difference for FA on the pistons. Not for Porsche heads. It also goes back to how much bang for your buck would you get out of it. I beleive there is a value to it.

That IC is very good for your application.

If you want a set of bolt-on headers for a Twin Turbo setup, contact Todd Knighton at Protomotive. He'll give you a good price. Tell him I sent you. I know Todd well.

Thank you guys,

I'll post some pictures soon. Just received my new 7.5:1 935 style pistons, etc - phew.

Will check out the Protomotive stuff but have also got the option on a local set - will get more detail.

Keep the ideas coming please.

Tom

I know of people who have used the 993 NA headers for a twin turbo setup. This typically mounts the turbos (usually Garrett T3 Super 60's) at the rear of the engine, like the 935's, gravity drain the oil into the chain cover housings, with the two exhaust dump pipes out under the middle of the bumper. Looks and sounds MEAN! If yours is just a track car,this would be a good setup. It's functional and those turbo's would spool really quick with no muffler :D

Have the two 40mm or 46mm Wastegates dump to atmo too :cool:

any photo? thanks in advance.

Sure, here you go :cool:

http://forums.pelicanparts.com/uploa...1126654158.jpg

All you'd need to do is fabricate a J pipe from the collector portion, mounting the two small turbo's in front of the respective chain housing covers.

Get the oil feed from the oil pressure switch at the top of the engine, and gravity drain the oil back into the lowest point in the chain housing cover.

The only problem with this configuration is it's difficult to use a muffler, however, if the car is purely track, you can dump straight out the rear :D

No silencer - no need to.

What is your take on the manifold length? From you pic it is clear that the 993 exhaust manifold is VERY uneven.

On NA cars exhaust tuning is key - what's the story on Turbo's?

I happen to have a 993 system here, so it really sounds like an idea.

Tom

T3-60 are souped up Garrett T3's. Pretty cheap turbochargers. They usually flow around 260hp worth of air a piece.

Much cheaper option is buying two used units from Volvo 740 Turbo or early SAAB 900/9000 turbo. They are oilcooled and can be had for <100$ a piece. integrated wastegates (no need for external ones). Base boost is often set @ 0.45 bar for SAAb units. They flow around 230hp of air but spin up sooner. Clearly a cheap alternative.

Re: ROUND TWO
 

I think custom intercoolers are better idea. Factory intercoolers were always quite bad. By fabricating your own, you can customize it so it fits your engine bay. 993 intercoolers are compromise made to fit 993 engine bay.

Here's one pix of custom IC on a car i'll be working at next spring:

http://www.itsfun.nu/itsfun2/itsfun2_198.jpg

WOW! What sort of tail is going to house THAT monster IC beepbeep? I hope that IC is easily removabe for servicing etc? :eek:

cookie porsche - ideally, for a TT setup, u would want to have short primaries (shorty headers) for optimum spool-up, but if you want to do a TT setup on the cheap and are not worried about looks, the 993NA headers have worked quite well. Just ask Mike Rombotis (mike the mechanic) who lurks around on these boards.

He's actually running a pair of Garrett Hybrid T3/T4 Turbo's :eek: AND he said they spool up very quick! Well, quicker than what his single T04B use to ;)

Thanks for the details on the 993 stuff, Merv.

Tom, after glancing at this post I believe that you are worried unnecessarily about how to reach 450bhp.
First of all your 3.0 crank is stronger than a 3.2/3.3 crank.
Second:a 3.2 intake flows enough air to give you well in excess of 600 hp at reasonable boost levels and will not necessitate any adapters.
Third: the 964 cams will give you all the power you want, but fall off well before the 7000rpm you are hoping to achieve. Best choice here is to have your heads ported and have them subsequently flowbench tested and contact one of the better cam grinders to recommend one of their grinds so you can achieve the powerband you are looking for.
Fourth: mill your heads 1mm to increase your compression to help your off boost power and transition coming out of turns.
Fifth: a GT2 intercooler set up will work out fine for your requirements.
Lastly: 55lbs/hr injectors can easily support 550bhp and when sizing exhaust headers don't get sucked into large diameter pipes. 1.5in will give you the power you are looking for as well as good throttle response. Larger will make more power but sacrifice response.

Good luck, Oliver

P.S.: as far as I am aware the 930 oil pump is the biggest pump Porsche ever made, but a 964/993 pump will work almost as well, just don't forget to put the factory top end oil restrictors on your motor to give a bit more oiling to the bottom end considering twin Garrett or Turbonetics turbos use upa large quantity of oil.

Wow - it took you guys a little time to wake up but now we're cookin'... thanks all. SmileWavy

The reason for the 450bhp was the assumption that to be competitive and RELIABLE for races lasting up to one hour, pushing the bhp too far may cause other problems. I have a big oil tank and huge oil cooler so that no problem - more worried about sustained use? A road car may accelerate under 100% load a few times every week but a race car does so almost full time.

The reason for the 7000rpm was that our gearbox is 'geared' to fit a powerband btw 4000-6500. The thought was that for those few extra-long straights that last 500rpm would allow max speed.

The car is already fast with the current NA engine - so I can only imagine what's to come...

UPDATE: The heads have been flowed, new valves, guides, twin spark and ceramic coating.

What should I do to the cylinders (Nikasil). I have cut a small 'eye-brow' for better case flow - but should I do anything else :confused: . The cylinders do have a ring-groove - what type of ring should I use?

Keep it coming ;) .Tom