GTR Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
194 Posts
Discussion Starter #1
Advice please guys and girls....

Considering the following two options. Give me your opinions.

Either


1. Full Steel Bottom End, standard CC. Loads of Revs = loads of power

OR

2. 2.7 / 2.8 conversion. More cc =more torque.

The cars running stage 1 mods at the moment (391 BHP), and I'm just planning my next stages. I don't want to go higher than 600 BHP in this one, just very quick and driveable. Will the standard bottom end do?

The cash is there, I just don't want to chuck it in the wrong direction.

Any help/thoughts/experiences greatly appreciated.:)

Andy T.
 

·
Registered
Joined
·
1,885 Posts
The bottom end is supposed to be ok for 500-600. I think the crank is ok for up to 700 odd..

If I were doing this I'd go for a 2.7 kit. This seems to be a happy compromise between revs and torque.

If you look at the spec of some of the serious cars they are any of the above though.

I'd go for the one which will be most future proof. torque will always be more driveable than if you have to rev the nuts off of it to go anywhere.

And with the 2.7 the bottom end will be done for the future so you'd only have to do it once, perhaps a nice balanced crank on top though.
I dare say you will get bored with 600 bhp after a while and want more,then you can re do the top end mods without too much drama. (if anything can be done without drama at these power levels)

Quote by MarioGTR on the max bhp thread in the tuning section...

"Another interesting tidbit: We have tried everything from de-stroking to 2.4 litres through to a full 3.2 litres - in the end, we stuck with 2,700cc. We used 87mm x 75.7mm - because, for reasons I don't have time to explain, an 86mm bore provides almost perfect combustion burn on Gasoline fuel (have a look at all of the best engines of the last 20 years, there is a reason for an 86mm bore - even the BMW S220 in the McLaren F1 utilised this) and the 75.7mm stroke (a 2mm increase) still allowed us to retain massive rev capability without any disturbing harmonics. Infact, the reason I limited the revs to 11,500rpm was the valvetrain assembly was borderline "

This was talking about a very serious car indeed !!

/Steve
 

·
Registered
Joined
·
194 Posts
Discussion Starter #3
Cheers Steve. Thanks for the input. I note in your quote that it appear's Mario is revving to 11K if I read that right? That certainly is beyond what I was expecting.

I know HKS do a kit for it. Any others recommended/in use?

PS. There's a reason for that power output, and I can assure you I won't get bored;) . I'm looking for an Evo 5 again to complement the Skyline, so money will be spent there too:( .

I just want it to be able to handle easily the amount of power I throw at it, hence I want to do it right, and being up here in Scotland, it's an expensive and long way to go if you get it wrong!

Anyway, the turbo's will be here next week!:D :D

Andy T.
 

·
Registered
Joined
·
2,110 Posts
If all you want is 600hp, don't waste your money on the bottom end. You can readily get that power with bolt ons and it will be reliable (and you'll save a nice deposit for that Evo as well). If you want to get higher power, then you need to start changing stuff as the power goes up - pistons, then rods, then the crank (assuming all other supporting mods are done in synch).

Increased displacement options for the GT-R are plenty. All the big names make a kit (eg. HKS - 2.8lt; Apexi - 2.9lt; Trust - 2.7lt; OS Giken - 3.0lt; JUN - 2.7lt, etc.) so you'll have endless choices. As for which is the best displacement, you really can't go wrong with any of them unless you are building a very unique engine.

Cya O!
 

·
Registered
Joined
·
194 Posts
Discussion Starter #5
Thanks guys...

As I said, the reasoning behind it is two fold.

1. I'd rather it was over engineered, so I know it's completely bulletproof. Better to build for 700 BHP and only use 500 BHP IMHO.

2. If I ever do want more (don't think so, but you never know:D ) then that scope is available to me at less extra cost.

As I say, I've got a pretty clear idea of where I want to go with the car, so thanks again for the input.

I'll keep you all posted as to how I get on;)

Cheers,

Andy T.
 

·
Registered
Joined
·
426 Posts
When choosing a kit...I'd go for the lightest one (agreed on the 2.7L).

Assuming all te 2.7L kits are made of the same grade of steel then get the lightest as this will make the engine more willing to rev....

Also you might consider that either Guy or Gary (sorry guys can't remember which of you!) was looking into getting Ti rods...and lightweight piston heads to go with them...
 
1 - 6 of 6 Posts
Top