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Showing results for tags 'GT-RS'.
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Hi All, I've done some quick searches but wasn't really able to get any definitive answers for what I was looking for, maybe I wasn't looking hard enough Anyway, a friend of mine is looking to replace some leaky mild steel dump pipes he has on his skyline. They are custom 3" mild steel dumps. These go into 3" front pipes that run into a twin 3" cat back to just before the diff where it merges into a single 4". I believe the front pipes and cat back are CES items. He is on a bit of a tight budget at the moment for various reasons and can't afford to go CES competition dumps and front pipe combo ( almost $1700 in mild steel!!!) which was my suggestion. Are there any off the shelf 3" items available that anyone knows of, or does he even need 3" dumps. I was under the impression that the size at dumps and front pipes is most crucial in limiting restriction in turbine flow. (As well as placing turbulence at least 400mm away from turbine outlet. The basic specs of the motor are as follows: 2.8L stroker kit HKS GT-RS twin turbo kit Stock mild steel exhaust manifolds Oversize valves (inlet and exhaust) Tomei cams (268deg in/ex I think with the largest lift) The engine is making 550rwhp at present Custom 3" dump pipes (leaky as the mild steel is corroded under heat wrap) CES 3" twin front pipes CES dual 3" exhaust merging to single 4" at rear. Response is more important to him than outright power (if that has any bearing in suggestions). Thanks in advance for any guidance! Cheers Jamie
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Hi all, Have pulled together some info from the RB25 dyno results thread. Only considered some of the more common turbo options (for more data points), and have focussed on those which are internally gated. Turbos looked at were: HKS GT-RS HKS 2835 Pro S Hypergear SS1PU GT3071 Was originally going to do 3076 as well, but didn't find a whole heap of examples where internal gate was still used. Have put together two plots. One shows peak power vs boost, and the other shows some dyno curves. Dyno curves are approximate, as I only read off a handful of points from posted images. Also recorded a bunch of dyno curves in km/hr but cbf trying to convert as not aware of different drive ratios between RB25 variants (e.g. Stag vs Skyline). Might dig some more in the info later to see if any other trends (e.g. for intercooler types), but nothing was immediately obvious. Some observations from myself: You're not going to see benefits of the bigger turbos (e.g. 3071) unless you push higher than 16 psi. Those with cams seem to be consistently at the top of the range. i.e. cams are good. Best results were had with Neo engines, but also some strangely poor results with GT-RS. SS1PU looks very good, shame there wasn't more results. Strongest mid range from 2835 Pro S Some possible conclusions: If you only want to run 16psi, stick with GT-RS (GT28) sized turbos. If you want max mid range (3-5,000rpm) smaller turbine is better. GT3071 really shines > 5,000 rpm, and needs boost. No groundbreaking insights here. There's obviously a heap of other factors that come into play too, but hopefully is of some interest.
