GTR Forum banner

1 - 20 of 22 Posts

·
Registered
Joined
·
78 Posts
Discussion Starter #1
Just trying to get an idea of the max achievable power 7 boost levels from a set of R34 N1s (.64/.64).

Any experience/views appreciated.

Thanks.
 

·
Registered
Joined
·
4,146 Posts
My power graph shows 450bhp at 1.3bar, so at 1.4bar I could probably get my hands on 500bhp :D Thats plain old R32 N1s aswell :cool:
 

·
Registered
Joined
·
2,056 Posts
I'd be surprised if an increase of 0.1 bar releases an extra 50 bhp. However I am impressed by your torque - 400lbft seems very respectable from a 450bhp car.

I know someone with R34 N1s running a very safe 1.2 bar and is getting 460bhp @ hubs. Mind you, that's not with stock cams.
 

·
Real men use a H-Pattern.
Joined
·
12,028 Posts
jza80 said:
460 @ 1.2 is very impressive. What cams are those?
Not sure what they are to be honest. I know they are HKS and they are mild cams, possibly 264s. Car is on DJetro without AFMs.
 

·
Registered
Joined
·
465 Posts
So, 500 whp with cams and stock internals, 100 octane, it would be hard pressed to get out of the GTSS or N1s?
 

·
Registered
Joined
·
2,056 Posts
I would guess so. I saw a Dynapack graph of a 2.8 with GT-SS turbos. Topped out at 480bhp @ hubs which it reached at 6000rpm and then held for quite a while until it tailed off.

Got to say though, for a car with 480bhp @ the hubs, it would have been damned quick due to the huge area under the graph.

The question is, when you say 500whp do you mean at the wheels themselves (which stop where the tyres begin and is what you'd see on a Dynapack ;) ) or do you mean at the rollers/tarmac ie once you've taken tyre losses into account?
 

·
Registered
Joined
·
465 Posts
Great question. I say 500whp, because I use a place that has the front and rear roller type dyno, so the car is fully assembled with wheels and tires. Not sure what kind of dyno or what it is called.

So, I guess to take out tire and wheel variations (weight, diameter and etc.), at the hub might be better for comparison sake.

Am I right here?

If so, is there a ballpark percentage that we can use to go from "at the hubs" to "at the wheels" HP figures?
 

·
Registered
Joined
·
2,056 Posts
legalr33 said:
If so, is there a ballpark percentage that we can use to go from "at the hubs" to "at the wheels" HP figures?
LOL how big a can of worms do you reckon you've just opened? :cool:

I don't know whether there's a definitive answer (assuming things like correctly inflated tyres, which makes a HUGE difference) but in the past I've seen lots of controversy from 2 camps about how power measured at the hubs compares to power measured at the rollers.

I'm not sure whether there was any agreement in the end but one thing is for certain - there are quite a few variables.

I think there are some people on this forum who have had their cars on both types of dyno but I don't know who they are. Ideally, we'd want sets of figures from people with different tyre sizes and different power levels so that we can establish a trend. I wouldn't be surprised if the relationship was non-linear.
 

·
Registered
Joined
·
465 Posts
Sorry for hijacking the thread, its somewhat related.

Goal: 100 octane, stock internals, but with cams, boost starting at 4000 or lower, 500 whp (give or take 20 hp, especially after the whole hub vs. wheel topic).

What are my turbo options?

I've been trying to answer this question for the last 3-6 months.
 

·
Registered
Joined
·
2,056 Posts
define what you mean by "boost starting at". Do you mean

a. postive manifold pressure by 4000rpm (ie 1 psi counts)
b. full boost by 4000rpm
c. 'decent' boost (eg 1 bar) if not full by 4000rpm
d. something else

?
 

·
Registered
Joined
·
465 Posts
Not entirely sure. I wish I was savvy enough to answer that.

Stock turbos start to kick in at about 3000rpm. I'd like to get as close to that as possible with uprated turbos and the specs mentioned in my previous post.

I was thinking, in exchange for the increase in HP and top end, I'd be willing to wait for the turbos to kick in at 4000rpm or lower.
 

·
Registered
Joined
·
465 Posts
Thanks for the feedback! I've been seriously considering the 2530.

Wasn't sure on the responsiveness of the 2530 matched with Tomei 260/260 9.15 cams.
 

·
Registered
Joined
·
2,056 Posts
Ideally you ought to get a ride in a car fitted with them so that you can judge the response for yourself.

I remember about 3 or 4 years ago going out in Andy Barnes' R34 before he had his major tune up. At the time he had 2530s and on the road was getting 1.6 bar of boost by 4000rpm. I'm not sure how common that is on stock 2.6 litre capacity but going by the controversy it seemed to cause I'm guessing it's not that common. However, as I don't have 2530s, have never ever driven a car with them and have only ever been in that one car that's got them, don't quote me on it!
 

·
Registered
Joined
·
2,056 Posts
I gather that 2530s are normally more laggy than that. Andy's car was well sorted and would have had a lot spent on it other than just changing the turbos. All of those things would have contributed to the response. Don't assume you can just slap a pair of 2530s onto a fairly stock car and get that sort of response because I very much doubt you will.
 
1 - 20 of 22 Posts
Top