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Discussion Starter #1 (Edited)
I have recently finished putting the car together & had it mapped on a rolling road with rather disappointing results. The mapper was unable to add any more ignition advance in order to make power as it had started to knock & pulled he the timing back again.

Engine Spec:
Standard RB26 bottom end
-5 turbos
Tomei turbo elbows
Tomei 1.2mm head gasket
Tomei Poncam type As
Tomei adjustable cam wheels (have not been adjusted yet)
Sard 800cc injectors with ballast resistors
Nismo adjustable fuel regulator
Splitfire coilpacks
Link G4 ECU
Top secret catch can
HKS Silent exhaust, de-catted
Koso aluminium rad
Greddy hard boost piping
Uprated fuel pump (cant remember what one)

It was only able to achieve 425bhp 316ftlbs at 1.4bar, much less than I was expecting for that spec!
IATs reached 45degrees on the dyno but have not been higher than 19degrees on WOT pulls
Compression test did not show anything wrong with good equal compression over all 6 cylinders hot & cold.
Fuel Tesco Momentum 99

Any ideas or suggestions on what may be causing it to struggle to take any more ignition advance & therefore make better power, I am hoping that it may have been a bad batch of fuel so will run through a couple of tanks of fresh fuel before going back.

If anyone has similar spec to mine and could share their ignition table so I could compare with mine that would also be a big help
 

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Tomei adjustable cam wheels (have not been adjusted yet)
This little bit sticks out for me! Why would you fit these parts with uprated Cams too if you are not going to adjust them to fully use the timing performance advantage these items are intended to give with your other engine modifications?!

JM2PW!:)
 

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You should make well over that even with the cam pulleys set at 0. I would say that assuming your fuel pressure reg is set to standard pressure or more then it***8217;s the fuel. I have had a bad tank of momentum and I won***8217;t use it any more. Shell is the way forward. I can share my ignition map, I***8217;ve just got to get my laptop with the software on it. My spec before was similar with stock cams and I made 503 bhp when it was peak summer at 1.4 bar (30 degrees ish ambient.)
 

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Discussion Starter #6 (Edited)
Thanks for sharing your ignition map, once the laptop charges I'll compare it to mine.

I don't think fuel pressure is contributing as the injectors are only at 78% duty and when the mapper added fuel at the point of knock & it made no difference, hoping it is the bad batch of fuel. Problem with Shell V power for me is I'd likely use half a tank between my house and nearest Shell garage to fuel up!

The cam pulleys haven't been adjusted yet as I am planning on doing this once running correctly and then make adjustments, carry out a dyno pull and see what effect it has on response etc.
 

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You should make well over that even with the cam pulleys set at 0. I would say that assuming your fuel pressure reg is set to standard pressure or more then it***8217;s the fuel. I have had a bad tank of momentum and I won***8217;t use it any more. Shell is the way forward. I can share my ignition map, I***8217;ve just got to get my laptop with the software on it. My spec before was similar with stock cams and I made 503 bhp when it was peak summer at 1.4 bar (30 degrees ish ambient.)
Weird you say that, I use Tesco all the time as the only time I've had bad batches of fuel it has been from Shell

To the OP, my car makes another 100bhp with smaller turbo's ( GTSS ) and standard cams
 

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What kind of spark plugs are you running and do they all look normal? Between your fuel and ignition system, are any of the parts old enough to consider they might be failing?
 

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Discussion Starter #10
Plugs are NGK BKR7EIX, they look normal, slightly rich but not too bad.

Majority of the ignition system is new, coils, plugs & harness are all new. Again majority of the fuel system is new injectors & fpr, fuel pump is a couple of years old.

Ignition table below:
 

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BKR are ISO plugs and 2.5mm shorter. Correct ones are BCPR which are JIS. You can easily pull the spring on the coil to make sure you get better contact with the plug tips.
 

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How does the car feel? No chance it's just a low reading dyno, it seems a lot of UK tuners do made up engine HP numbers which usually look really inflated - so comparing with those could cause disappointment.

Also, no sign of a triggering upgrade - something now that these things which are getting on is getting very worth addressing. Could be ignition scatter, how "smooth" does your power curve look?
 

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Discussion Starter #14
Car pulls very well, definitely much better than before, the car was in a mild state of tune prior to this however, comparing it to other cars I have owned of similar power/weight I would say it feels about right for that power.

Power curve is pretty smooth
15713449028057509094404872471826_1571344933036.jpg
 

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Some ideas:

Could the cam timing be a tooth out?
Could you have really high exhaust back pressure from a CAT or restrictive exhaust (are HKS silents rubbish, and you dont mention down pipe)?
Whats the condition of the intercooler?

My car made more power than yours with stock turbos at slightly more than 1 bar on abbeys rolling road
 

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Jimbo makes a really good point

Another thought is
- exhaust gas leak before turbo
- Boost leak
- Were valve clearances checked after fitting the pon a cams. Is there possibility the valve clearances are tight and effecting compression when the engine is hot

Both would work the turbos much higher than normal and lead to reduced tolerance to ignition.
 

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Discussion Starter #18
Some good ideas there.
The cam timing could well of shifted so will check that.
Exhaust wise I'm sure I have read of people making much higher power using the same exhaust? Theres no cat or restrictive down pipe, down pipe is aftermarket but unsure of brand. No signs of any exhaust gas leaks either.
Valve clearances were all checked and adjusted to within spec when the cams were fitted, there were only 4 valves that required adjustment.
Externally the intercooler looks in good condition but haven't looked inside, the IAT appears to be healthy during WOT pulls however.
Power figure is at the flywheel
 

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Before I comment I'd need to know what fuel pump you're using and ideally what model of car (32, 33, 34).
It could also help to let people know what you were expecting HP or KW wise - 450hp to MOST people on the road is BIG power but on the drag strip is very pedestrian.

I can comfortably say that i had issues with injectors fully opening but being let down by a fuel pump that couldn't flow enough. I replaced mine with a Nismo option and the injectors now get to about 40 - 45% duty max on 15psi (factory internals)

I make just shy of 450hp at the flywheel (34 V-spec, Link g4, fuel system, exhaust and intake upgraded, factory tubbys & cams) if it helps?
Cos I can't put the image in, you can see my dyno sheet here
 
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