Moving anything to the left on a power graph usually requires detuning and results in a net HP loss Im afraid. Looking at the AFR plot, id be fattening it up from 4000rpm down and perhaps adding some ignition (subject to detonation) to help flatten that hole in the power curve for starters. Incremental gains but worth the bother. Id be looking at fitting smaller,l quicker spooling bb turbos and doing further breathing mods to keep the torque peak as high as it is. Some clever cam profiles may help here but i reckon they will cut top end a little. The engine shows very little power drop off up high so look to extending your RPM peak to beyond 7 grand, say 8000, which will have the effect your after but only with a slight diff ration change if you are using stock 3.7. If you already have a 4.1 ratio then you can suck it up and think about fitting a 4.3 or thereabouts subject to peak straightline rpm. Think an R200 diff setup for circuit work. Only other alternative is to add a gear ratio with a 6 speed. IMHO of course. Cheers E
why has this been past. this is a very good point in my mind. what is the exhaust housing size wiz? 0.64 ? surely a size smaller would shift the line to the left, obviously what you would gain down low you will loose some up top... guess like the comparison with auto and manual turbos, auto smaller exhaust housing, faster spool etc... pretty much related to what andymac suggests with going a smaller exhaust manifold .... going smaller on the exhaust side of things
i agree, They say that the only important thing on a turbo engine is the turbo. Simplistic but pretty accurate.
Pretty much The conclusion i came to after reading all of the above, plus numerous pm's i received from knowledgable people, plus talking to others who aren't on the forum. Only downside of going smaller on the exhaust side is loss of power up top and more heat generated. Really what i have is good, just wanted to see if it could be made better, changing gear ratios or fitting a six speed box would solve the problem, but as stated, how much do you want to spend?
I think if you maybe went from the auto to man cams you would have had a better result. But again up to you if you want to do that. The suggestions of going to standard manis would be a step backward with 2860 turbos as its always been the case of "2860 larger manis to get the full potential".
If it's running GT2860 turbos then I would not be happy with the present power output and particularly the power spread. Those turbos are good for over 300whp each so are obviously too big for the rest of the engine, exhaust etc going by the dyno chart. So either upgrade the rest to match the turbos or go with more realistically sized turbos. See Black Beast here, good stuff http://www.aus300zx.com/forum/showthread.php?t=310824
What's not To be happy with. Only three in front of it on the dyno list, but not built for the dyno. Power spread is as good if not better than most on here, overlay some of the maps. The figures Black beast is showing is from the slot car running race fuel, water meth and god knows what else. Plenty of engine for the turbos, all built. The same bloke that tunes the slot car is the same one who tunes mine, he's happy with it.
thats right Ron going smaller on exhaust housing (.48a/r is the option )defeats the purpose of running GT28RS (noob suggestion) and makes them less efficient/more heat. continue with your breather mods and dont go look backwards.. did you say six speed?
Bumping this thread back up. I have been looking at ways to maximise spool, actually searching for info on adjusting the cam gears. Anyway. I'm sure everyone knows I bought Ron's zed early last year. Thus far I have been working on improving on all the good bits it already has. Increased injector size first, as the nismo 555's were at their limit and I wanted to run more boost to make the most of the GTX2863's. Also added selin and twin (split) intake prior to last tune. This resulted in 535.9hp at 22ish PSI. At this boost we were getting spark blow out before tuning was complete. Next round of (hopefull) improvements included removing FMIC and replaced with 2.5IN SMIC and full 2.5IN pipe kit, 54mm throttle bodies for breather mods (hoping to improve spool) and also HKS DLI Ignition Amplifier to help run larger plug gap with increased boost. Have another tune coming up end on Jan which will hopefully be the end of power mods until down the track if I decide to go E85. Will post dyno here to compare however it won't be a fair comparo as the 535.9hp was not optimised.
The FMIC I had on there is a great cooler and flowed well. I changed to SMIC purely for ease of fitment of the 2.5in intercooler pipe kit, and not having to have 2.5in FMIC pipes made up to suit the rest of the piping.
Wow ' you must be near as old as me ,have not heard the word scramble for years did a bit myself back in the late 50's.
Torque out of corners wins races. HP good for top speed. Longer induction length will lower when max peak torque is obtained.
Old Z Owner I am 74 how old are you, I can remember Stan Jones raceing the Mayback in Parramatta Park, Jack Brabam's Cooper Bristal at Mt.Druett and Art Senier 's Arial at Bathurst. Moore Bank scrambles ,the Vinyards short circuit track and Fairfield show ground. Plus more circuits in NSW I can name
