Christer

I am just saying its impossible without trial and error.

For example, my car has 3.8 Cup Pistons and slightly longer cams than a 'Motec +2' package from 9M (which the last time I looked was a 3.6)....it might be reasonable to expect that my car will make maybe 5% more power as a result of the added volume and the slightly longer cams but in fact it barely makes a few HP more....but it does hold the power for longer...so what I am saying is....this has to be tested...in each application....and that is why I am guessing that Colin is not going to make any firm claims on this because it will matter to a very large degree on the particular car's setup....

With regards to chipping....I don't have a lot of faith in that in any case. But again, it does again depend to a large degree from car to car I would imagine - based on differences in the condition of the engine etc. So therefore, a chipmaker might claim 20HP and when someone gets 1HP they say 'oh yeah, well thats probably because the engine is tired or the MAF isn't working or whatever'....I don't mean any offense to any 'chipmakers' out there, but people like 9M will tell you what they expect to achieve and then deliver. I think its too easy for claims to be bandied about with the excuses that follow....at least some chipmakers are offering money-back guarantees and thats good (as long as they are in business)....but it would be great to find out whether there is a factual basis for comparison between a number of cars so that 964 owners can decide (without using their ***) whether a particular chip is worth it...and that is why I and others have always performed dynos before and after each mod...like the GHL system I have...(or had installed)....its not just for my benefit - it is also for everyone else's benefit...maybe i was lucky to get around 20hp and 20lb/ft from my GHL but this was what the totally independent (and cynical) JZM crew found on their dyno on the same day when the old system was swapped. It would be great to see others do the same, but usually its a false economy thing..."I just spent USD2400 on an exhaust system but I can't see the point of spending another USD150 to check what it is that I got".....and that is the type of mentality I don't understand.....yes, I am guessing there are not many multi-millionaires around here but I don't mind spending another USD150 once in a while if it a) puts my mind at rest, and b) helps someone else out in the future......

Can I breathe now....and........aaaahhhh.....

Red rooster

Geoffrey/Christer,
Exactly ! There are so many claims of performance increase out there that I guess the cynic in me always says - prove it ! Geoffreys suggestion of optimisation with ONLY the heads swapped would put this to bed.

I am pretty sure these 9M heads do work but the improvement numbers do seem to be "what we would normally expect" versus "what we got today ".
With the variance in apparently identical motors that maybe isnt good enough .

Ah well , back to work.
All the best,

Geoff

Chris M.

Really? Who has one?


993 with 9M heads

c

Red rooster

ChrisM,
You have 9M heads on your 993 ? Any power figures ?
In Europe 300+bhp 3.6 motors are plentiful. Any tuner who couldnt get that kind of power with cams etc would not be in business long !

Geoff

tonytaylor

9M has packages available that take the 3.6 over 300hp without the new heads. I believe he is on record as saying this is easier to acheive with the 964 than the 993 and that the new heads are aimed at solving difficulties in increasing power in the 993 due to its sub optimal head design.

I've been quoted approximate power outputs for an engine rebuild ( that is unfortunatly approaching soon) with and without the heads and while the difference in bhp/torque expectedis not insignificant the extra cost is.

Christer

Tony

Eaxactly, the cost of the heads as part of larger work is not an issue - its only when people are looking at it from a 'bolt-on and see what it does' viewpoint that it becomes one. That is why I have been saying all along that the heads are just a small part of the package - if you have a budget of say USD1500 to improve the performance of the car then my advice is to wait until you have more....the 200 bucks here and there on chips and so on are only detracting from your future *worthwhile* performance mods.

Red rooster

Thanks guys for the input. I think Christer has missed the point of what I am trying to discover. Looks like nobody knows what extra bhp these heads will give ! Geoffrey has hinted at 14 bhp.
Maybe one day someone will be able to quantify this expensive product so we will all know what we will get for our money.

Now , how much was that light pressure turbo kit ? !!!!!

All the best

Geoff

Christer

Yes, no one knows because it will depend on a myriad of of variables as already discussed. In one situation it will be 22hp perhsps, another only 10 or whatever. If you were ever to become a client of Colin's and you discussed a particular project with him then I am sure he could give you an overall target power output if he had tested the combinations. Why don't you just ask Colin?

robmug

Geoff - where did you get the 14bhp figure from - you've mentioned it several times, but I can only find Geoffrey's posts mentioning 414bhp...perhaps I've missed something...

Red rooster

robmug,
Geoffrey was talking about 398ish on standard heads and 414 on 9M heads.

OK, so it could be +16bhp or about 4 % . On a less radical motor running around 300 bhp that would imply +12bhp at best.
That is the kind of number that different inlet/exhaust set up could cover.

Still leads to the same situation. Build a motor with lots of modifications including 9M heads and measure the power. What would be the difference with properly prepared standard heads . No one knows !! We are told the answer is less power by the guy selling the heads.

This is NOT an attack on 9M but just trying to see what the money buys !!

I think that is called common sense .

I suspect the answer is a tangible benifit for a ***** out motor but little for a street modified where the airflow potential will not be used.

I guess the answer is to wait and see what happens when motors are built.

All the best

Geoff

robmug

Geoff - OK, I get it. My take on it is that the heads are what restricts the ultimate power gains achieved; so at xxxbhp the heads are what stops a tuner going any further.

So there may be gains with just the heads, but that's not what they were designed for.

Geoffrey

Lets step back a minute. The engine is an air pump and the more air you can get into the cylinder, the more power the engine is going to make. On any engine combination, improving cylinder filling will always give you benefits in terms of torque, power, throttle response, etc. So, on a perfectly stock engine there would be benefits from using a better head. However, if you factor in costs, you'd probably do other modifications FIRST, or in conjunction with better heads, be it Colin's or not. As mentioned earlier, 320hp is possible with some basic modifications.

The 392-398hp from Colin's engine were from a PORTED set of factory heads, not stock. You could not get 392hp from a stock set of heads, they simply don't flow that well. So when you guys say only 14hp, that is not over stock, but over a fully prepped stock head which has been ported.

Red rooster

Geoffrey,
Understood. At around 400bhp this must be approaching the limits of the air cooled motor ! All pretty exiciting stuff for race cars but for the street ??

Be interesting to see what your racer does !!

All the best

Geoff

AVoyvoda

"At around 400bhp this must be approaching the limits of the air cooled motor" Not too sure about that...

Colin's 3.8 race motor generates 414 hp. At 4.0 litres - what he's building this moment - power should increase in proportion to displacement, reaching say 436 hp (+5%)

A similar 4.0 litre motor but de-tuned for street, could be looking at 380-400 hp or thereabouts...

Before anybody starts raising questions, the answer is: we'll know - for sure - in a couple of months.

Red rooster

Maybe Colin should offer that motor to Porsche for the 997 GT3 !! Beats their 4 valve ,Variocam efforts !!

Geoff