Freebaggin

Does anyone run or has seen or knows where to buy an off-the-shelf HKS exhaust manifold on their RB25? I can't remember where but I've seen an HKS cast manifold that from the outside looks like stock but I assume the guts of it is better designed for high HP and flow. I have an internal gate Garrett turbo that is bolted onto the stock manifold and I want to see if I can get a better flowing off-the-shelf manifold rather than having to get someone to do a tubular one. Thanks in advance.

B-Man, that's gonna be fantastic mate, like you say, you've got the support gear to go with it and you'll be able to rev the tits off it to make use of the power band shift to the higher RPM. Interesting the difference between the Garrett and HKS GT3040 CHRAs: Garrett Comp, trim = 56, 60mm/82mm Turbine, trim = 84, 60mm, 55mm HKS Comp, trim = 50, 58mm/82mm Turbine, trim = 84, 60mm, 55mm Minor differences in sizes. With that 1.12 housing it will be huge power!

Black33, if you take a look at the setup you'll see that the line from the manifold to the top of the BOV is used to hold the BOV closed under BOOST. The pressure is imposed on the diaphram in the BOV works in conjunction with the sping. The spring is there to keep it closed under vacuum and therefore no leaks as well. The line you are blocking off feeds onto the diaphram but in the opposite direction to the manifold line and OPENS the BOV under boost (maybe above 12psi). So there is no risk of the BOV opening under boost, I spose that's the whole point of doing it, no leaking under boost and therefore let the boost controller do the controlling, not the BOV.

The guy who posted this originally has the GT30-40 intended for an RB20, so the 0.87 A/R would be crap. Joel, I was thinking about a better wastegate actuator as well. I don't really have a major problem anymore, holds 17psi well with the BOV mod I did. I still don't quite understand how a harder spring would make a difference, although I haven't really thought about it either. Thing is, I want 8psi for around town and if the spring is set at "14psi" then I assume it will remain shut until that boost is reached? No good. I dont intend runnign more than 17psi (1.2bar) anyway so I might be fine with the current setup, woudl rather spend on cams and nice exhaust manifold.

Yeah, good stuff from the big ute mate! By the way, how is the ute event overall?

Yeah mate, we'll teach him how to use them.....it'll be a double Garrett + Microtech Boost Worx vs HKS + PFC Tilbrooks WHIPPIN!!!!

Yep it was fun, pretty steep learnign curve. Especially when we started out in the mid thirteens and ended up with the times we got. Joel, spool up is not THAT much different between motors, I have stock exh manifold, plenum etc that might help with spool up as my compressor and turbne wheels are bigger than Grepin's but he has Greddy plenum, tubular exh and other nice high flowing stuff. Might end up doing that swap Munro.........can you do no clutch flat gear changes with those gearboxes Grepin was slack and did not organise his own cameras!! So no one has anything?

Hmmmm, interesting stuff Hungry6. I might have to eat my words a bit re RB25 at least. I see power drop off at 6300rpm odd as well, not much but enough. Might look into the 0.82 later down the track. The louder exhaust might be due to the lower exhaust back pressure. I made basically no other change on my motor except bigger turbo (up from stock) and it was louder for sure. However for RB20, I reckon even with the 0.63, the lag might be alot.

Steve, great to see your turbs is reponding better now with the ECU change. Time to hit AIR :wassup: Need some decent tyres mate. Believe it or not I am runnign ZE-326 Falkens and they are pretty good on the strip!?! I still reckon the GT3040 would be very laggy with a 0.82-0.87 turbine housing. Two things: 1. Steve is running 2.5L with VVT. Not 2.0L with no VVT. 2. Steve's GT30307S has a smaller compressor wheel. Anyway, depends what you want I spose. I'd say you will have to rev to well over 8500rpm to get the benefit and by the the RB20 head may have run out of flow anyway.

How do you knwo 0.63 is small? Check my post above. You haven't put yours on yet, might be a lag monster. Guy here changed from 0.61 on HKS 3037 (bit smaller comp wheel only compared to 3040) to 0.87 and went from 256rwkW @ 1 Bar with full boost at 3500rpm to 280 at 1.2 bar but no boost until 5200rpm. Would be heaps slower on the road. Gotta remember the A/R is a ratio, not an absolute number so if you have a big exhaust wheel then the area inside the exhaust housing will also be big to maintain the ratio of 0.63. And it's the area that gives the flow at the top end + the exhaust wheel diameter.

I have GT3040 BB CHRA with T04B 0.6 A/R comp housing machined out. Also Sierra Cosworth internal gate exh housing with 0.63 A/R. I'm using 0.6 comp cover so that it clears exh manifold. All support sfuff is totally STOCK except injectors (550), FMIC and Microtech. So stock exh manifold, inlet manifold, cams and throttle body. I am getting 265rwkW (Dyno Dynamic) at 1.2 bar with power dropping off a fraction above 6300rpm, but still 250-255 at redline. I have "full boost" at 3800rpm. I am very happy with setup but definately less responsive than stock turbo below 3500rpm . I wouldn't recommend 0.87 exh housing, would be too laggy unless absolute top end power is wanted but then only worthwhile with nice tubular exhaust. Heaps experienced tune shops here recommend 0.6 odd A/R, heaps of power can still be made. So that's the only other thing, I reckon mine would respond really well to nicer exh manifold.

Thanks Whats, much happier, Shaun at Boost Worx really put in the effort and care needed and the important thing is the way it drives not the numbers so much. Steve and co., no more RE540s in Oz left!!! Running them out for the new RE55 which is CRAP, just ask Chris32, only lasted 3000km, whereas Grepin's (and Whats's) RE540s are not quite as grippy but have lasted a long time with a good old caning. Fantastic tyre the 540, pitty. Bridgestone comming out with harder compound RE55 to address durability issues as there are a number of race categories that are really pissed off with the swapp from 540s to 55s. I think late March for new rubber. Other dissapointing thing is the new RE55s are asymetric.

Turbosmart e-Boost EBC. The fluctuations in the boost curve are more to do with the Microtech MAP sensor reading the natural pressure spikes that occur in the inlet manifolds of engines, these spikes are usually not seen, i.e. smoothed out with boost guages.

Thanks for that. I thought he'd prefer to get rid of larger portions, so smaller is better for sure. You got good grunt from dyno runs today I hear, are you happier? I have had a good run in the last day or so, basically tidying up tune and boost leaking from stock BOV. I've gone from 250 to 265 at the same boost (1.2 bar) and heaps more mid range. Car fells totally different, feels like it's ready to kill me!

Great, that would be good mate. I need 1m x 1m I suppose. Let me know.

Well I suppose it's more that the turbo might be running more efficienctly as well, not having to increase shaft speed to counter the bleed of and as the boost chart shows, the curve is a smidge more consistant and maybe that's all the turbo needs to provide better grunt..???

Yep.

Thanks to you for sure, I had basically forgotten that the stock BOVs leak and your post promted me to do something about....fantastic result for the cost and effort involved!

http://www.skylinesaustralia.com/forums/sh...3706#post633706 I'll post up the Microtech engine data log of before and after that will show boost curve as well.

So, I did the BOV mod, consisting of a "machined" PVC irrigation plug placed into the BOV leak line and we got the result I was after. Initial run was with line open (stock setup) and then placed the plug in hole and the result as attached. Didn't need to adjust e-Boost sensivity as boost response was good and also good up to 6800rpm then dropping off. So for 10c I got 8-10rwkW from 120-180km/h, so it helped both top end boost and boost spool up. Getting better tune tomorrow as A/F ratio was in the 10s in the mid range and timing too conservative (14-15°). I still feel there is more in it up top so a mech. flow restriction might still be there.

Thanks guys. Steve, what would Tils have done with the gear you "gave" them.

I'm having trouble locating some mesh for my new front bar (minimum purchase from one place was 12m by 24m, yes meters :thumbdwn: ). Do you guys have any suggestions? I am after diamond style mesh with the diamond being about 2cm by 1cm. Thanks in advance.

Spoke to Grepin just then Steve and he explained the SAPOL/Regency situation to me more clearly (i haven't really read this thread properly sorry :Oops: , I've just stuck my head in the sand and hope I never get defected). However it sounds like the situation here in SA needs addressing for sure. The other ridiculous thing is the holiday road toll is bad this year across the nation and the blame has been flung back at us supposed SPEEDING drivers. The fault it is bad is surely with the road safety policies of the bloody state governments!! Does anyone subscribe to Wheels, they now have a regular section on this issues, it's great. The average driver is getting more and more cynical about the SAFETY benefit of the cameras and guns and therefore not careing anymore. Even my father-in-law, the slowest driver I have ever met, has been camered twice in the last 6 months!! Anyway, this issue and the defect issue goes hand in hand and is not benefiting anyone exept government coffers. The idea of a multi club movement is good.

Is the defect/import situation really THAT bad relative to other states?? I have heard lots of horror story for NSW, Vic and WA guys. Steve comments like "And leave the narrow mindedness that plagues SA..." really pisses me off!

Steve, where is your evidence? Why don't you detail the specific examples you mention and provide all the data and I assume the setups were all the same? Tell me about the 3040 example. Without thorough back to back studies of each we just can't assuem that there is a huge difference between the two. Why can't you just leave it at the fact that HKS turbos are good and Garrett turbos are good and that HKS turbos are NOT massively better...jeez, what a hard head.