Building a 3.0L engine

Been to see my engineer friend and he reckons the best way to get more is to strengthen up the bottom end and have a high comp running no more than 1 bar on the standard turbo!
Obviously a standalone ecu is required.He has never heard of adaptronic and was concerned that it may not be quick enough to react to what the engine is doing, as compared to say an Omex or Pectal system.

He seemed to think that 300bhp from the 2.5 litre is relatively straight forward.
As he said,its all ok to fit big turbos and cams etc etc, but if you design the engine to give you more relative torque to bhp then the car will be quicker. (i am talking road not track)

I've got the Z7W engine withe the 9.5:1 comp pistons
If the combustion area in the Z7W heads is 51.59 cc
and the combuston area in Z6W is 53.3 cc
and the pistons are both listed as 9.5:1 what would be the comp ratio

They are different pistons (dome height)

I was thinking you had a Z6W engine, and could fit smaller combustion chambered Z7W heads (though its not just that simple)

Been to see my engineer friend and he reckons the best way to get more is to strengthen up the bottom end and have a high comp running no more than 1 bar on the standard turbo!
Obviously a standalone ecu is required.He has never heard of adaptronic and was concerned that it may not be quick enough to react to what the engine is doing, as compared to say an Omex or Pectal system.

He seemed to think that 300bhp from the 2.5 litre is relatively straight forward.
As he said,its all ok to fit big turbos and cams etc etc, but if you design the engine to give you more relative torque to bhp then the car will be quicker. (i am talking road not track)

Oh dear....here we go again!!! His name isnt John and he isnt from the US is he??!
The Renault factory didnt manage 300bhp from the engine on the standard set up and Tony with his 3 litre version on the standard set up is knocking on the door of 300....but it hasnt been simple, trust me. Your engineer friend obviously doesnt know the engine if he thinks its simple. I would start by speaking to someone who understands the problems.
The Adaptronic is as quick as any ECU....I have it fitted as does Tony. Again, your friend doesnt appear to know what hes talking about....sorry!

No he isn't called John and he lives in Devon.

He admits to not knowing the engine and its weaknesses openly, but a man who can build an old Sherpa engine,(in a maestro Turbo),to 380bhp (at the moment,there is more to come as they are having difficulties with the mapping),does know what he is talking about.
The trouble is,is that we are talking £££ and £££

He has got 304bhp out of a 2.5 normally aspirated cosworth engine!!
It just takes lots of money as when he builds his engines they are built to be reliable.

The phrases you used were 'straight forward' to get 300bhp and 'using the standard turbo'
That in my books isnt 'costing £££s'
The thing about John was a joke......hes someone from the US who claims to have a 400bhp PRV....until David sorted him out that is!!

Hey, i'm not looking to pick a fight here with anyone.
I can only let you guys know what he has told me,obviously the proof is in the pudding!
He has a lot of experience with engine building so hopefully we can come up with something good.

Forged pistons were first on the list and then getting the comp ratio to about 9.5:1!
Don't know if this setup would need to go with strengthened rods or not though??
He did mention going the twin turbo route,but still insisted on only using low boost though. It will be interesting to see how DG's setup goes with regards to power and torque.
Roller bearing turbo was also mentioned,again he was referring to torque.

Ah, but I often find 'old blokes' that do/did alot of naturally aspirated tuning in the past don't understand the concepts of turbocharging and hence always talk about upgrading the internals, raising the compression etc...
If I stuck the turbo off a GTA on that 300bhp n/a Cosworth, it would actually lose power...

On a turbo engine, the turbo and the exhaust are the key fundermentals - the bit in the middle (the engine ) isnt actually that important...

Imaging I had a standard Z7U with a turbo and manifolds that could flow 400bhp, and somebody else had a fully built 3.0 engine, with the best cams, valves, pistons, head work and stuck a turbo/manifold config that could flow 300bhp...

Now 'potentially', which one could make the most power?. I could in theory hit 400 depending on boost, intercooling, revs etc..but no matter what, the 3.0 will never hit over 300bhp, no matter what it does. Even if it is bored out to 9 litres....

Hence these days we see turbo'd 1.6 hondas doing 500bhp on stock internals..

I see exactly where you are coming from DG. I remember the old Renault F1 turbo engine was only 1.5 litres producing upto 1500bhp in qualifying form.
But big power isn't everything,perhaps i am thinking more along the lines of torque.
If you have a car with 200lb ft and one with 300lb ft regardless of power,surely the one with the most torque will accelerate quicker!!??

Everyone seems to be striving for the 300bhp mark but is this going to give you the quickest car?

I see exactly where you are coming from DG. I remember the old Renault F1 turbo engine was only 1.5 litres producing upto 1500bhp in qualifying form.
But big power isn't everything,perhaps i am thinking more along the lines of torque.
If you have a car with 200lb ft and one with 300lb ft regardless of power,surely the one with the most torque will accelerate quicker!!??

Everyone seems to be striving for the 300bhp mark but is this going to give you the quickest car?

Then have both. A car specced for 300bhp will still have over 300lb/ft, such as Petes...

If you build an engine for 400bhp, you are going to see nigh on 400 too, just later in the rev range..

Yes, a car with more low end torque will get away quicker, but then it also means its just going to tail off quicker, whereas the 300-400bhp car will be getting into its stride and streaking ahead.

Horses for courses, but I don't recommend raising the compression and running less boost. You might as well just put a standard 2.8/3.0 lump in and bolt the turbo back on....

At the end of the day i suppose its down to driving style and what you want to use it for.
Any particular reason why you wouldn't go the high comp way DG?

It will be interesting to see how you get on with the twin turbo setup,how's it coming on?
I am in no great hurry to build this engine,so will be best for me to learn about everyone else's experiences first.You guys have been doing this a lot longer and i know there's no substitute for experience!!!

Any particular reason why you wouldn't go the high comp way DG?

Firstly this engine runs very hot and runs very mild, low lift cams which adds to the actual cranking pressure inside the combustion chamber. The cranking pressure at the mo at 8.6 is nigh on the same as the 9.5 with the better cams.

To relieve this, you could run higher lift cams etc, but you couldnt do this on a Z7U, as the piston domes are high to begin with...sowith higher comp pistons you would probably run into problems...

I think what your guy is thinking, is by running high compression and low boost you have no need for a big turbo, but it doesnt work like that as I said previously. X amount of horsepower needs X amount of CFM.

My biturbo config is almost done, end of the day its just all bolt on parts, I need to get other bits on the actual car finished

Once the biturbo kit is done and running and gets some results I will then build a serious single turbo setup and work with that too...

It is easier and more cost effective in the long run to work with a single, as it also makes upgrading the turbo cheaper too if more power is desired.

.. as a matter of interest, how much more portential does the A610 engine have for tuning over the GTA... given its even fire, 3 litre etc...?

.. as a matter of interest, how much more portential does the A610 engine have for tuning over the GTA... given its even fire, 3 litre etc...?

argh! , as I said, its all about the bits on the engine that make the difference. In theory 20% more, but on the other hand, the short stroke 2.5 with work might be able to rev far higher than the 3.0, or take more crank loading without failure, which could make it more power.....(in the extremes)