Date: Tue, 11 Jul 2000 17:37:54 +0200 From: "Mads Lund" <Mads.Lnopsamin.Dk> Subject: Re: Turbo specs on 9-3, 9-5 needed
> I am not at all a turbo expert (or even an amateur) but I have trouble > understanding why you want (need) a turbo bigger than a gt17/T25 or equivalent > on a 1.1liter engine? These turbos can produce up to 350bhp in a 2.3l car, hence > they should be able to move all the air your bike can breath.......even at > 15000rpm..... First of all, the Garrett GT17 I'm using on my bike (900ccm) is working fine. No turbo lag at all ex. if I open the throttle out off a corne with a initial rpm of 6.000 and acc. up to 10.000 before changing gear, when I open the throttle does the manifold pressure rise as quickly as the throttle opens, so that's perfect. When I draw it up from the bottom (3.000 rpm) does the pressure rise from 0 bar at 4.000 to 0,5 bar at 5.500, and from that point does the wastegate maintain this pressure to redline. The situation is that with higher boostlevels (max 1,1 bar) and a larger capacity engine does the turbine and wastegate produce a back pressure against the engine, that can (and does) cause problems. the result is that the temperature of the exhause valves is too high, with detonation as result. And my experience with detonation and aluminium pistons is ..... expencive. So in order to lower the temperature is the larger turbine needed. The goal for the ZZR1100 turbo engine is to produce 250 hp at 1,1 bar pressure. > In my ignorance, I though that for a bike, the number one priority would be to > have a small turbo with very quick response and short spool up? And the mitsu > 15T used in the aeros introduces noticable lag even in the 2.3t engine compared > to the smaller t25. On a bike engine, this must be complete dead ....... Sure, my ZX9R does not have any problems (except the rear end power slides when the throttle is hit too hard out of corners ;-) But from various ZZR1100 projekts are the preffered turbo sligthly larger than the GT17 > Please explain to me why and how a gt17 or t25 can be too small for your > application (I have assumed that you are installing it on the bike....)? To me, > it sounds more like you need to put some effort into the software controlling > all this..... Thats another side of the projekt. At the moment am I using a manuel boost controller, but I have a electric valve assembly, with 3 valves in it, and by diffrent nozzeles in the valves is it possible to cheat the wastegate in 8 steps. The idea is to control the boost level either mannually or by a gear indicator, so 1. = 120 hp, 2 = 140 hp, 3 =160 hp, 4-6 = 180 hp, and having a extreme posision so the 900 ccm enging can produce 200-210 hp on the rear wheel. One of the problem with variable boost level is that I dont have EFI on the bike, and the carburation is quite boost dependant. But since I have boost controlled fuel pressure and pressures the carburators, do I have to work a little on differating these pressures according to the manifold pressure (in general reducing the fuel pressure more than the boost pressure is reduced according to the max boost pressure, so the fuel consumtion reduses when the boost level is reduced) Or put in the 3000$ to a programmable EFI. Mads Lund Ninja9RT
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