LambD - I thought everyone is only allowed the same type of 34mm restrictor for boost.

eg.

http://www.adgespeed.co.uk/albums/parts/restrictors.jpg

http://0101.nccdn.net/1_5/17b/0ab/1c6/24mm-res.JPG

I thought long runners improved torque on small engines also while staged injectors remove heat from charge higher up and nearer the valve from the valve and head as mentioned. However with so much capacity in the inlet maybe its not as important? Also intercooler size can be an issue?

sikyne, i was more pointing out that newer injectors have come out that have a higher cc rating and can still get perfect idle. Designed for bike engines. aiming at increase the power curve not to increase hp. As you said from your dyno run that its much hard to tune the secondaries. Methanol fuel have secondaries more often to cold the boosted air +cc rating example rotor motors :) i sure you know that one. Looks like you reach max hp at that rpm + boost i guess head work bigger valves could help top end with increased rpm.

D it's a 36mm restrictor for single turbos, 2x27mm for twin turbo engines.

Quote:
most broke arse S13 owners who "upgrade" to those manifolds a) use cheap China copies of the Greddy style plenum who's only design criteria is to look like the Greddy manifold, and b) don't have the sort of modification levels the Greddy manifold was designed to work with. They were not designed for your average 200rwkw street engine... RB26 ITB manifolds also don't work well on RB25s. They're designed for different engine characteristics.

Torque production in a forced induction engine is far more about when the boost comes on than how long the manifold is. In a race engine that should be turning to almost 9000rpm, producing good torque at 3000 is pointless - you'll never use that part of teh rev range, and should be trying to optimise the upper part of the rev range you'll be using in a race...

theyll be 34mm soon if turbos get too far ahead ;)

if the twin turbo has a window of 52mm (27 x 2) then why arent there any BMWs M3 like racers using a destroked magnesim 6 N5X out there

27 x 2 doesn't equal 52

Diameters cant be added together as a means of comparison either

so in fact 27 x 2 is more like just over 38

Quote:
because you can make more power from the non restricted NA 6 or 8s with less weight and not have driveline breaking torque, just to name a few reasons.

Ask BSM how much it costs to make a LM twin turbo competitive!!! and to keep it going for a season.

woops thats 54mm curtain much like comparing 2v versus 4v heads.

Good to know Harry the BMW engines cannot make more as 1.3 twin turbos :) they are pricey enough! i was looking at the cheaper M52B20 engines as they are cheap at the wreckers and so are 80s 323 series Bmws these days and more available than datsuns or other rwds

The 3 cyl 1.5 twinpower (sc and turbo) can make 55kw per cylinder and has smaller inlet manifold design but has the SC also so will be interesting to see if smaller volume manifold will perform better.

This thing is just amazing. Well done and I see you even managed to get 270hp atw for a short run. YEEHA

I haven't updated this for a long time... I ended up building another bottom end for this. Still standard rods and crank but using a set of old Arias forged pistons. The domes were machined off and the ring grooves were made wider in the lathe to suit a set of 2mm rings I had. The head is still the same H89 with the slightly larger valves and ports.

I reduced the inlet duration on the cam and widened the lobe separation, both to reduce overlap.


I've also gone to a RB20 gearbox with a close ratio gear set.

This year I'm not racing as I have lots of other projects on. So this wont see more development till later this year.

Hi Sikyne slightly off topic but i am very interested in how you make a rb20 gearbox fit an a series. Do you have any pics or a thread on how you did this? is it simply cutting the bellhousing and welding a A series one on?

also does it use a custom clutch to suit a rb20 input shaft?

thanks!