Lithium

Nice! Let me know how it goes, I'll wait with interest Zahos: Just do what I do, wait for somebody elses misfortune and vulture them when they just want to biff the turbo :headspin:

Yeah, I know about that way around it - but I would rather not

Haha - I'd love to One of my friends blew his R32 RB20DET turbo recently, running ~18psi through it :headspin: This is how I am getting one so FREE, I just happened to think of it when I was pondering how to alter my boost actuation. How long have you been running 13psi through your stock turbo??? Thats pretty up there...

Hiya all If you've seen the "Pushing a mostly stock R33" you'd know where this question comes from. Anyway, I have an R33 Spec2 and would like to run ~2psi more boost and hold it properly. At the moment I have a GFB bleed valve controlling the boost level, but it bleeds off quite quickly after peak boost is reached - though I know that the Rb20DET turbos seem to run a couple psi higher boost than the RB25DET ones, so theoretically if I used the same boost control they do I should get similar boost behaviour - so wouldn't really need to rely on a bleed valve. I can get an R32 RB20DET turbo for free, does anyone know if I can use the actuator/actuator spring with the RB25DET turbo? Any thing I should know? Cheers in advance! Dan.

Yep, definately - the S-AFC2 has a knock readout, and I tend to mess around with settings on the dyno

Well, seein as you are running 13psi (so probably drop to 10-11psi) - quite a bit from 4500rpm (where they seem to peak) up to 7000rpm based on the boost plots I got for my car. I should really scan them and post them. From memory 1psi (slightly less even) boost at ~6700rpm gained me ~10rwkw at that point. I got 202rwkw on 9psi, with 9psi coming at ~4500rpm and dropping to ~8.5 at peak power - and got 211rwkw peaking at 11psi @ 4500rpm, dropping to ~9.5 at peak power. Of course mid range still gets some pretty decent gains

Thanks for the input guys It looks to me to be pretty much what I expected (seeing that people with FMICs and dp/fps have the problem too) which is that the factory wastegate is behind most of the problem, so I am guessing that an external (or replacement internal) wastegate would improve it a lot - though an AVC-R would probably do quite a good job of tricking it into holding boost as well. Might have to nick a wastegate actuator from someones broken RB20DET turbo and experiment - we'll see

Good point - that would be quite a good idea, though where is the "13.5" magic number defined? What pressure drop is it assuming etc? Shame its not feasible to attach a tacho to the turbo hehe Most people talking about 13.5 as measured at the plenum afaik. I am just after 11psi (or even slightly less) right through the rev range, I'd just like more "area beneath the curve" - and think that up-and-down boost running isn't the best way about it.

Hi all! I am trying to improve the all around performance of my Spec2 R33 GTS25t while maintaining acceptable reliability, and not spending huge amounts of money or having the car being obviously fairly modified. At the moment it has a 3" catback exhaust, Pod filter with cold air box (and ducting), removed charcoal canister a GFB bleed valve and an S-AFC2 which has been dyno tuned to run at 11psi, which I don't want to go past with the stock intercooler and turbo. The thing I have noticed, that when looking at the boost plot from the dyno tuning - it reaches 10.5psi quite quickly (2400rpm), creeps out to a peak of 11.3psi (momentarily) at 4500rpm and by the time it reaches its peak power at 6600rpm the boost has dropped back off to about 9.5psi - where peak power is attained. The "base" dyno run I did for some reason peaked out at 13.6psi, and dropped back to a minimum of 11.5psi - interestingly enough that was before it had a bleed valve installed!? Anyway - what I conclude from this, is that the factory wastegate is not much fun - and is obviously opening earlier than I want to, stopping the car from reaching 11psi straight away - but then after it reaches that peak it stays more open than it needs to be and the boost is dropping off, as opposed to the turbo running out of efficient flow. The most obvious sign that the car wants to push harder, is briefly as the boost is dropping - it levels off from its decline at around 10psi for a few hundred rpm between 6000 and 6500rpm and there is a corresponding increase in steepness of the power curve until the boost starts dropping again, where the power curve returns to being almost flattened off completely. What I am thinking about doing, is installing an Apexi AVC-R and getting that tweaked to allow it to hit 11psi straight away (ie, ~2500rpm) and hold that until the end - in an effort to increase torque, and also keep the power curve climbing at the steady rate it appears to want to - possibly gaining me near 10kw @ wheels peak power, but most importantly having it so its not dropping boost in my "working area" of 4500rpm -> 7000rpm. Question is, I hear the factory intercooler has quite a significant "pressure drop" across it - due to inefficiency more than cooling effect, and I don't want the poor stocky to be revving its nuts off to supply 11psi at high engine rpm through a restrictive intake system. Will this be a dangerous amount to push the turbo? Any experiences with Apexi AVC-Rs and boost behaviour using them? Any help would be very appreciated Dyno plot from the final tune at 11psi for reference should be attached:

The RB25DET turbos have a ceramic-type exhaust wheel, and as far as I understand at high speeds/temps they can break off and head off for more carnage - so its not just efficiency thats not going to be ideal. But on efficiency, as far as I understand a turbo's efficiency is measured on turbine rpm vs. air type scale - so maybe an RB25DET demands in the same area of turbine rpm from the turbine for 12psi as an SR20DET does to be pressurised to 17psi, being a bigger motor and all.

Yeah, it was great having an exhaust probe in there tracking things - and spotted some shady boost behaviour etc. It lays everything out on the table for you. I'm just using an S-AFC2

Yeah, cheers Its quite funny, because I'm (obviously) really stoked and I was talking to someone recently who realised what my new power figure was and didn't see why I was quite so happy. The power figure is good, but getting up and going - and pulling through the midrange is meaty as anything. Feels like the 2.5turbo has been pulled and a big NA motor that revs to 7000rpm has been put in, 10-11psi is being reached by 2400rpm (lower than I expected - not sure what normal is). The area beneath the curve makes it feel to me like an all around much faster car, and just more pleasant to potter around in too I definately rate dyno tuning as a very important step - even without trying it at the strip... its obviously made the car more responsive etc, which has to be worth something in practical terms.

One step closer, raised the boost to 11psi and got it dyno tuned - feels like a completely different car. With the current setup I figure very solid 13s should be achievable, I think a bit of work including other-than-power stuff will be needed for a 12 .

With a tear in my eye, I can honestly say - thats beautiful :wassup: Very nice setup there, look forward to hearing about how it actually works out!

I know its clutching for straws, but check all your piping which gets pressurised - you could have blown an intercooler hose or something like that, car is throwing in fuel for air it isn't receiving when it comes on boost. Just adding a possibility to the mix :headspin:

Its all about traction with FWD NAs, one of my friends did 13.7 with the above mods + semi slicks on a non-TypeR 1.8VTEC Integra. The VTECs go very well for NAs, my old VTEC Prelude managed 141fwkw with basic bolt on modifications + dyno tuning - which gave it pretty respectable (even by turbo standards) acceleration, though bare in mind in NZ most of our cars seem to be Jap versions - which go better than the non Jap ones right from the start. Obviously, no way near as much fun as a Skyline - missing the RWD factor primarily, but if you have to worry about insurance etc they are definately a good idea. I bought the Prelude to keep me happy until the expense of a turbo was something I could live with A normal VTEC Integra with basic mods will even make a very good car to blat around in until a turbo is doable.

Very difficult, but possible - I have watched an R32 GTSt w/ RB20DET run an 12.2 in NZ, but that was using NOS and slicks. Esp. if you want to do it with a road car/street tires, I'd guess an RB25 would make it heaps easier - just because of the response/turbo driving ability.

Settle Gretal, he was sticking up for you from the people changing the topic to a vs. conversation. Worded differently - "All he wants to know is who has done a RB22DET, or how is a good way to go about- because that is what he wants to do".

That would be cool But yeah, realistically in NZ people more often than not short change R33s - so they have hardly been bothered with... most people prefer the R32s, and see them as a better performing car - so thats where more of the knowledge lies, and there is a lot of assumption. Obviously in Oz you guys are more keen to mod R33s and research ways of getting the better results... so its always good to look where the proven information is, rather than ask people who more often than not don't even like R33s, and in many cases havent even been in them how to mod them - so aren't exactly reliable sources

No, not at all - I haven't had any problems with mine at all... but so far I have only been running around on stock boost, untuned SAFC and a catback exhaust - so no real stress for it YET I run 255s on the back so I am a bit worried that after the car is tuned with a bit more boost - it might get a bit more upset. Anyway, keep up the good times guys! I'll watch with interest how you guys are going and see if I can get an R33 representing a little in NZ as well

Awesome! Congratulations, thats very impressive without heaps of mods. In NZ the quickest R33s are barely touching into the 13s I'm just a n00b here, but I have been quietly tracking your progress and soaking info, because I have been building up parts for my R33 - and your car for a while had very similar to the mods I decided to do for my "first stage" (cold air intake, cat back exhaust, and S-AFC2) and read quite a few posts re: your car and S-AFC tuning which looked very positive for the direction I was heading. What clutch are you running?

All I was doing there was setting the facts straigtht - the only R33 you have officially raced you got beaten by, and the R34 did an ok job considering how few mods it had relative to you given it won the first race - you both had the poor traction disadvantage to contend with. The difference in mods thing (in favour of the R33) is part of my point, you said yours is faster than most of the 33s around - all of those are a lot more stock than yours, and yours is also quicker than the equivalent r32s.... it was a pointless comment. Also, the GTSt that ran low 12s - you said in your post low 11s (so even if you were told high 11s, you were twisting facts), and ask him yourself why he was using the NOS - and he was using NOS all the way from what I remember him saying. Ask him yourself, he posts as Trust Dunn on Skyline forums. I didn't realise you already had a RB25DET crank - if you do, then I the 2.2 idea sounds very cool.... if you don't (the only RB25 cranks I know of at your place belong to Mark and Jeff)... I'd considering the RB26 crank, as you dislike Rb25s so much - and given the amount of work you'd have to do etc, a 2.4 would be a lot more rewarding. You can borrow my HPI mag on their build up ideas of an RB24DET (rb20det based) - basically in concept the RB24 would be at least as torquey as an RB25, and still be based on the RB20DET block- so you get your cake and eat it too

I hear some whale defending necessary! You have hardly any other RWD skylines around which can keep up with yours, and from memory the ones that have at all are 33s or 34s (ie, RB25 powered). From memory the only R33 you have raced at the drags beat you - and all the other 33s around here are virtually stock (at the moment), and all this is with the RB25 in the heavier body. Also, dyno figures wise - the R33s on average are way higher powered at CF than the R32s, yours with bigger turbo, S-AFC etc was in the middle of the cat-back exhaust and pod filter R33 brigade - so the RB25s are actually making more power too. An R33 with a road tuned S-AFC and bigger turbo would be in a whole different power/performance class. The GTSt you mention was doing low 12s on slicks, and needed NOS because with the RB20 was unable to spool the turbo well enough for a decent launch - and has a built RB25 now.