sten gr

Hello engine eksperts!

I am in the planning process of building a race engine out of a 964 engine I just bought,
And I need some help and advise. I am nothing but an amateur in engine building so please bear over with me if I ask stupid Questions and have unrealistic wishes and goals.

350 hp would be nice and longevity to. Since the track I have the biggest issue with is quite tight, I want (if possible) the power band to be wide like 5000 to 8000 rpm.
Gas in Norway is 98 oct but I am also considering to run on ethanol E85
The rotating mass should be as light as possible to improve response

The parts I am considering are:
964 (76,4mm) crank
Con rods: Arrow Precision 132mm and ARP bolts
Smart racing rod bearings (or is OEM god enough?)
Gt3 oil pump I believe this has an additional pick up point witch improve oil pressure under hard braking?)
Ninemeister 103 mm race piston or similar from JE
103/109mm Ninemeister ore Nickies
ARP head studs
964 Heads intake ported and intake valve increased to 50mm, 8 mm valve stem
Jenvey single throttle body
Larger injectors

I have absolutely no idea what cylinder/head gasket to use or cam profile or length on the intake, or the recommended valve spring to use.
Please feel free to comment on this especially on the length on the con rods and the choice of not using 102/109mm Mahle p&c.
Will the rockers cope with this rpm?

Exhaust from http://www.stigsgarage.se/
below


Sten

Fast4525

This sounds like a great project but I don't have too much advice to give.

Have you considered using Motec system and 9M heads? This would make it much easier to reach your power goals Also, for a tight track you might want solid power lower than 5000rpm unless you plan to re-gear your G50.

What is a "Jenvey single throttle body"? The exhaust you posted looks brilliant, do they offer a version with heat?

Good luck!

sten gr

Motec or most likely a ”home made” engine management system will be used.
Gear box has 8:32 ring and pinion (not 100% sure on the numbers but it is re geared)
And I might change the ratios on 3,4 and 5 It does 235 in 5 and I don’t need more than 200 km/h
http://www.jenvey.co.uk/
No option for heat on the exhaust.

Thank you.

Geoffrey

You'll really need to sit down and design the engine as a system for it to work properly. For instance, if you run the 132mm rods, then you need a custom piston, one with a reduced compression height so you can maintain the proper deck clearance. I am not a fan of JE pistons and they are not anything like 9M pistons and you'll have to run 2-3x the piston to cylinder clearance on the JEs as you would on the 9M. The good thing is that you have identified your powerband range 5-8k. This means that you'll need a cam with long duration and narrow lobe centers. From that information, you know you need raised compression to keep the dynamic compression up with the longer camshafts. However, you also want to run 98RON fuel, so you have to keep that in mind. With the longer duration cams and lighter valves, you'll need to determine the spring pressure required on the seat and nose. From that information you can find a spring that will work for you. This list goes on, and on, but that is what you need to be thinking about as you design your engine.

sten gr

Hello Geoffrey

This is from Ninmeister home page:
3.1 103 Race Piston
The original Championship winning 103.0mm 9m Racing piston for all 964 & 993 engines up to 4.1 litres. CNC machined from an isothermally forged billet of 2618A aluminium alloy. Short skirt slipper design reduces friction at high rpm. Optimised intruder design increases side squish area to improve combustion, compatible with standard Porsche and 9m billet heads.
76.4mm throw crank , 132.0 rod = 12.8:1 compression
80.0mm crank & 130.2mm rod = 13.4 compression
9m Part: 9mR10310301 4T Part:

So I assume the deck height is OK.

You wrote: However, you also want to run 98RON fuel, so you have to keep that in mind.
I’m not sure I understand what you are saying her? Are you thinking of detonation issues?

Race fuel is not allowed but E85 is and if it is available I want to map a program for this as well

Thanks for your input, it is highly appreciated

Sten

Geoffrey

Yes, if you use a 9M piston with the rod length it was designed for then the deck height should be fine.

Depending on what camshaft you run, you may or may not have to adjust the compression ratio. It sounds like you might be better off buying a 9M package which includes everything you've listed. Pistons, rods, cylinders, camshafts, and 9M ITBs. That way it is designed as a system.

Christer

Hi Sten

Having gone down this route, I can only advise that it is a very big project indeed if you are looking to select all the parts etc. yourself and then having someone do it and then expect good results. As Geoffrey has said, the whole package needs to work together in order to deliver good results at the best price possible. In my humble opinion, it would be best by far for you to drive your car over to the UK; and give the car to Ninemeister/9M in Warrington and leave it there for a couple of months, as they can supply, engineer and generally cover the whole project for you in one place. 9M are the only ones that I know of that can do all this for you.

I would give Colin Belton at 9M a call, tell him what you want and he will give realistic advice. Although I have spent a lot of cash with Colin, in certain cases he has also saved me money by being open and honest.

Lykke til!

TR6

First question that needs to be answered is what club/race series/class are you planning to race in. Many of the items you've listed may disqualify your car from certain classes or series. Start the project by reading the rule book for the class you plan to race in.

sten gr

The rules for the cup in Norway are quite liberal, so this is luckily of no concern.

I realize the easiest would be to just deliver the car to a qualified shop like Ninemeister, but I want to do this my self.
And since I am an amateur I was thinking I should ask the pro`s about the choice of parts to make a reliable race engine.
Another thing is the exchange rate
I’m not trying to put together a completely new design but want to use parts we (we is actually you, rennlisters) know work well, so far it seems I should stay away from JE pistons.

Are the rockers capable of handling 8000 rpm?

Anybody know the price for Ninemeister 103mm piston and cylinder?

Charles Navarro

I can tell you we run .0015" total piston to cylinder clearance (then coat the skirts if so desired) on our 103/107 (slip fit) and even on the 105/109 Nickies, with no problem, since our alloy is very well suited to the 2618 forging alloy. We also have a proven ringset we've been running in these bore sizes for years now that works great with the nikasil plating with the proper low tension rings.

There are a few guys here in the states campaigning their race cars with these really big bore cylinders, like the car that did 25 hours at Thunderhill just a while back with the 105s. You just need to make sure whatever you do choose, that you're legal. No sense in spending all that money to have something that is not legal. That said, the 103s or even the 105s are perfectly reliable, even for the street. As far as it goes with the JE's, you get what you pay for. A $1000 set of JEs is very different than a set costing $1500 or more, with quite a few of the options most people don't even are offered.

Christer

Hi Sten

Seriously, I would re-consider doing this all yourself unless you want to waste money, potentially *a lot* of money. I am not telling you this to spoil your fun but in order to save you pain. Believe me, this is a lot bigger than you know now........

I am willing to help as much as possible, but at the end of the day the selection of parts etc. is only about 10% of the job done, the rest of the 90% is actually putting everything together to work in harmony which someone else will have to do. The problem is that if you get the 10% even partially worng, then the end result will be 90% wrong too.......get the person who will do the work to be involved in your selection process.

Christer

Sten, this is another area of concern to me, and one area I also struggled with when I was building my engine. I would *not* be asking anyone on an internet board which cam to use, because uinless you know which pistons you are going to use, which compression you are going to run and which fuelling system you are going to use and so on and so on and so on then its a waste of time, but more importantly could be a waste of money and you not getting the right result. EVERYTHING hangs together in a build like this, EVERYTHING. I insisted on using 3.8 Cup pistons in my enginge, when I could have listened to 9M (in this case) and got 20HP more by using another.

One very important question though: who is going to build the engine?

tonytaylor

Based on personal experience.

If it were me I'd entrust the build to a pro who can show results of the build you decide on. The potential for mismatched parts is huge. What you think works or should work often doesn't work quite so well in real life.

Firstly it would be good idea to put a number to your budget. A similar build to what you are discribing would run to about £15k at 9M and produce around 350hp.

It's important your budget is fairly elastic.

Secondly perhaps you should consider the time frame you envisage for the build. Even if you get it proffesionaly built it can take longer than you might think. A lot longer.

Thirdly it's worth reconsidering why you are doing the build. If you have a thing for aircooled track cars then that's fair enough but the cost of a build like this would go a long long way towards a GT3 for example.

Finally IMHO there is about 100 other improvements that could be made to the 964 for less money that would give bigger improvements in performance of the car.

Larry Herman

I too suggest that you know your own limits. Re-building a stock motor can be a nice hobby, and there are a few guys in our club who have re-built theirs several times. I would only consider having a reputable pro build a race motor. The stresses are so much greater, and the knowledge required so much more that you just don't want to try that yourself. Having 9M do it would probably be your least expensive and most reliable option.

NineMeister

The build specification you propose is not too far away from the 3.8 litre engine I had in my 993RS a year or so ago:

1. 993 crankcases, windage ported, 109mm spigots
2. Stock 993RS crank & oil pump
3. Carillo 132mm rods (built before we started making our own)
4. 9m 103mm race pistons, 12.75:1 compression, 1.0mm squish
5. 9m 103 x 109 cylinders, 9m steel sealing rings
6. 9m billet heads, valves, springs, retainers
7. 9m Race cams & mechanical lifters
8. 9m ITB intake system
9. 993 heat exchangers
10. 100 cell split flow cats & sports silencers

I clipped the rpm of this engine to 7800 due to the oiling limitations of the standard crank and oil pump. The only other item I would have liked to run at the time was a complete header set but I could not find anything ideal (hence why we designed our own system for the 964 and 993). The dyno comparison below is against a stock GT3 mk2 and a GT3RS, where it clearly shows a lot more area under the curve and proved to be a faster than the watercooled cars on track - I think the 0-100mph in my 993RS CS was sub 9 seconds.

If you are confident about your abilities you could assemble a similar engine yourself. If you kept the stock 964 heads & ported them and built the rest of the engine using the same parts you would end up around 30hp down from the peak numbers my engine made, which would still be at the thick end of 400hp and a lot more than your target of 350. That said, I definitely recommend against buying the components from different sources because you could potentially end up with a lot less than you expect. One example of this is the ITB throttle body system where you mention Jenveys. We use these ourselves, but have gone to the trouble of designing our own intake manifolds, airboxes and throttle cable/linkage so that they are a true bolt-on conversion, whereas if you buy the parts from Jenvey I guarantee you will spend hours getting it all to fit and work correctly.

I hope this helps & all the best with your project whichever path you take.