GTR Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
8,548 Posts
Discussion Starter #1
Hi folks, been thinking about cams recently and thought I would seek some advice....

Just to add some context for those that haven't been following my build....
Basically its a std capacity RB26 in a track ONLY R32GTR. At the moment I still have the std twins but intend to switch over to a GT4094r once the car has seen a few track days and had a shake down after a long period off the road. I am looking for maximum response and reckon on a 7300-7500 rev limit. I have adjustable cam gear and will be running Syvecs S8 management with 50/50 water/meth injection.

Would prefer to use Tomei cams and have it in my head that the 280deg 10.8 mm Procam would be the best cam for the job. Thats using the wet finger in the air approach but know from experience that folks tend to over-spec their cams.

To that end, I'd appreciate any input from tuners or those that are running a GT4094 on what they feel would be an appropriate cam choice with response as the main goal.


TT
 

·
Registered
Joined
·
4,586 Posts
Any reason why you are looking at an old turbo like the GT4049?
 

·
Registered
Joined
·
554 Posts
Hi I have the GT4088R little brother I know lol and pom cams type b and am going for mapping Wednesday next week I can let you know how it faired if you like ? I might even start a build thread lol
 

·
Registered
Joined
·
8,548 Posts
Discussion Starter #4
Any reason why you are looking at an old turbo like the GT4049?
Not really.... Just happen to have a refurbed one lying around.

I appreciate that there is better and newer but ill stick with the 4094 for the moment.


TT
 

·
Registered
Joined
·
3,583 Posts
The gt4094r is a good turbo see my thread with some comparisons in it. If your looking for the ultimate response and 7500 rpm limit then you will need the 0.84 ar housing which will still make about 650 crank hp. I have a 0.84 ar turbine housing for sale If you need one.

I made peak hp at about 7000 rpm on the small housing. I'm a straight liner so it's all about power for me hence changing to the 1.06 housing.
 

·
Registered
Joined
·
2,780 Posts
stick with twins for track,been there done it.
twins 400bhp @3000 rpm full boost 1.6 bar by 3300rpm. gt4094r great turbo had one. sold the car built a new motor with twins and knocked 14 secs of round Anglesey with 150bhp less
 

·
Registered
Joined
·
2,780 Posts
you need the linear feel around track unless you are able to carry massive speed in and out of the corners using full slicks and the car has a full welded cage in..
sell it and buy some trick diffs...
 

·
Registered
Joined
·
2,304 Posts
Surely you mean 1.4 seconds? I have a gt4094 going on my car, I have hks 280 step 3 cams I had a billet compressor wheel fitted to help spool the turbo. I would imagine water/meth injection will also help as the advance ignition what could be run? What inj kit you going to run? I was thinking about runing water/meth injection as I have a syvecs s6 so should be easy to run fail safes incase anything happens
 

·
Registered
Joined
·
3,583 Posts
14 seconds is an incredible difference, must have been off boost most of the lap!

my thoughts exactly, I don't get it, i believe its true but i think there must be a lot more factors involved than better response but 150 hp less.

i only have a 2.7 but as long as i keep the revs up the boost is there pretty quick.
heres a plot of me shifting and driving in 2wd in the wet on the big housing on a little 2.7.





and that's clutch and gearbox so ive gotta clutch down, h pattern shift, clutch up and wait for response to accelerate and get back upto the speed i dipped the clutch at, looking at the plot its all done and back accelerating upto and past the shift point speed in 0.4 - 0.5 seconds for a good shift which was 2nd to 3rd, the 3rd to 4th shift was just a lazy shift hence took ages as plot shows.
 

·
Registered
Joined
·
8,548 Posts
Discussion Starter #11
I had a billet compressor wheel fitted to help spool the turbo.
Considering this mod too....


I would imagine water/meth injection will also help as the advance ignition what could be run? What inj kit you going to run?
Thats the idea! Should see an improvement using W/M. Undecided at present about which kit but have shortlisted 2.....Coolingmist and AEM. I will use the ECU to control it all so really only require pump, lines and nozzles.

TT
 

·
Registered
Joined
·
8,548 Posts
Discussion Starter #12

·
Registered
Joined
·
2,304 Posts
Considering this mod too....




Thats the idea! Should see an improvement using W/M. Undecided at present about which kit but have shortlisted 2.....Coolingmist and AEM. I will use the ECU to control it all so really only require pump, lines and nozzles.

TT
Are you going to run some pressure sensors wired to Ecu on the injection kit? The aem comes with a failsafe sensor I'm pretty sure. Snow performance do some nice kits also.

I had my billet wheel done by cr turbos it was £250 supplied fitted balanced and delivery so for cost well worth doing IMO. What size rear housing do you have?
 

·
Registered
Joined
·
2,780 Posts
no 14 secs. the problem with most tracks with a large single is boost is very sharp when it comes in and if you lift your back into lag,with twins you can feed the power in smoother and at the same time be faster out of the corner. I have footage of both cars from in car. 2.00 mins full circuit anglelsey with the 30ltr and gt4094r and 1.44 with the 26 and low mount responsive twins.dont get me wrong I miss the 4094r sound and urgency but for me it was too late spooling. mine was even quicker than Scooby slayers in response terme.full boost 1.6 bar by 4600 rpm. but by the time I was about to get it I had to let of for the next corner and unless I kept the revs in the 5000 mark entering the corner I had no boost mid corner. but no matter how good you are on the gas its was very aggressive with very little pedal travel.
 

·
Registered
Joined
·
2,304 Posts
no 14 secs. the problem with most tracks with a large single is boost is very sharp when it comes in and if you lift your back into lag,with twins you can feed the power in smoother and at the same time be faster out of the corner. I have footage of both cars from in car. 2.00 mins full circuit anglelsey with the 30ltr and gt4094r and 1.44 with the 26 and low mount responsive twins.dont get me wrong I miss the 4094r sound and urgency but for me it was too late spooling. mine was even quicker than Scooby slayers in response terme.full boost 1.6 bar by 4600 rpm. but by the time I was about to get it I had to let of for the next corner and unless I kept the revs in the 5000 mark entering the corner I had no boost mid corner. but no matter how good you are on the gas its was very aggressive with very little pedal travel.

What gearbox was you using? Wouldn't that be a gear ratio problem? If that's the case why has the rk tunning and mgt racing track cars both got singles and not twins? What size housing was you using and what power was your car running?
 

·
Registered
Joined
·
3,583 Posts
no 14 secs. the problem with most tracks with a large single is boost is very sharp when it comes in and if you lift your back into lag,with twins you can feed the power in smoother and at the same time be faster out of the corner. I have footage of both cars from in car. 2.00 mins full circuit anglelsey with the 30ltr and gt4094r and 1.44 with the 26 and low mount responsive twins.dont get me wrong I miss the 4094r sound and urgency but for me it was too late spooling. mine was even quicker than Scooby slayers in response terme.full boost 1.6 bar by 4600 rpm. but by the time I was about to get it I had to let of for the next corner and unless I kept the revs in the 5000 mark entering the corner I had no boost mid corner. but no matter how good you are on the gas its was very aggressive with very little pedal travel.
I can totally understand the exiting a corner part my r32 is very tame and easy to drive fast out of corners with -7s 415 whp, whereas the gt40 is a monster when it comes on and gives alot more torque steer on my road tyres.
what was your rev limit with the rb30 ?
 

·
Registered
Joined
·
659 Posts
I don't know how a billet compressor wheel would help anything unless it was lighter than the cast Garrett item? (assuming they are the exact same profile also).

Is the head ported? What size exhaust and exiting where? What size A/R housing on GT4094?

If it is just a standard head with little to no porting then don't bother with any cams that will create overlap. Choose some mild duration cams (no where near 280°) with as much lift as you can get away with, with the stock spings... unless you are changing them? I would.

To be honest if it were me, I wouldn't bother upgrading to such a large turbocharger without some decent head work or an increase in capacity for a track car.
 

·
Registered
Joined
·
8,548 Posts
Discussion Starter #18
Bump for this..... Lots of talk about incidental stuff and no specific recommendations about cam choice..

So.... anyone???



TT
 

·
Registered
Joined
·
9,736 Posts
Avoid reverse staggered cams! I know a lot of people use them but there has been some testing done on a few sites inc supra forum that show while reveres stagger might help spool the turbo up quicker you lose power at low mid and top end. Equal cams for mid to top end and stagger ie more lift and duration on inlet vs less of each on exhaust. Also if you going for cams with higher lift more than 10mm make sure you consider recessed pistons and also upgraded valve springs.
 

·
Registered
Joined
·
8,548 Posts
Discussion Starter #20
Oh well, no sooner did I bump the thread that I noticed a set of Trust 264 9.7 cams for sale.

Decided they would be a good choice so decided to buy them.


I think they'll do just fine...



TT
 
1 - 20 of 20 Posts
Top