Harey

Hi all, I went to see a reputable performance joint yesterday about installing a HKS 2835 Pro S kit I have got my hands on. I already have a 3" metal intake to the Z32 afm and then pod. However, the new turbo has a 4" intake and the tuner is strongly recommending I move the afm to the cooler piping and run a 4" intake due to reversion and potential stalling issues arising when transitioning on/off boost. He said this seems to occur frequently with the larger compressor covers. I want to keep my 3" metal intake and leave the afm in the factory location. Even though the turbo has a 4" intake its not designed for huge power (280rwkw max) and from what I can see all the other guys running this turbo dont run 4" intakes. Has anyone had this issue? Or is it minor, the extra price of this work is scaring me off changing to this turbo.

Point to remember, just having a particular engine and turbo combo does not mean you will automatically make the power its capable of. So much depends on exhaust, intake, intercooler etc. You are 100% right, that engine and turbo combo is capable of a lot more power, but if you do not have all the required supporting mods as suggested above then you will not make the power and the tuner can only tune with whatever is given to him. You really need to build a relationship with your tuner and tell him what you want, then he can do testing and find out what is limiting things.

Interesting that the leaner dyno result made a heap less power?? Must have had a lot less timing. What exhaust do you have on it? I think its worth going back to the tuner and saying your not happy with it. That way you can see if he can get more power out of it or there is a restriction somewhere. You really need to let the tuner know what your expecting. The tuner might have noticed temps starting to increase and so left the tune there. He probably thinks your happy with it until you tell him.

Definitely doesnt look too rich. Were those two runs on different boost levels? Do you have the accompanying boost plots?

Post up the dyno sheet and we can see if its too rich. Tuners can be in a hard position because if they push things too hard and something fails they get a bad name. Although he really should listen to you and see what you want to do. Not sure what your talking about in the second half of your post??

The exhaust tester went overboard saying that there was no problem with the cat and I think your going overboard saying it does nothing. If you put a block of wood in the cat, the pencil guage would show a reading. I have a catco 3" cat and Trent from Status did some testing for me, see dyno sheet below - Yellow is full exhaust, Light Blue is no catback exhaust, Dark Blue is no cat or catback exhaust It would be more conclusive if he kept going till redline but it was dam loud and it looked so close so he stopped the run.

I dont think this test is applicable to testing for a cat causing a 20kw restriction. When the car is free revving there is no load or boost to contribute to air travelling through the cat. Its more a test to see if the cat is seriously blocked. I agree he should not say it is free as a bird as it is only a very simple test.

The standard injectors and standard air flow meter run out around 220-230rwkw (~300rwhp). DO NOT fit a different turbo if you dont intend on getting the ecu remapped. Go here: http://www.skyline-owners-club.com/forums/17490-nissan-skyline-r33-gts-t-tuning-guide.html Also are lots of good threads here: http://www.skylinesaustralia.com/forums/topic/66556-forced-induction-quick-ref-guide/

Just a note you would need to run larger than stock injectors to make 230-240rwkw with E85, which adds cost in both the injectors and more involved tuning. Even the standard AFM runs out about 220-230rwkw. So you would prob have to stop there unless you want to buy a Z32 AFM as well.

Woops I replied to a post on the first page not realising there was a second page where the questions were already answered!

A lot more than just one result. Subaru guys in the states have done back to back testing. Lots of info here: http://www.skylinesaustralia.com/forums/topic/344089-garrett-medium-frame-gtx-turbos/

Octane booster will make almost no difference to the AFR. AFR is air-fuel-ratio and the amount of fuel is barely changing (200mL in 50L+ of fuel). E85 uses roughly 25% more fuel just to make the same power. So the tune for E85 will roughly have 25% (rough estimate) more fuel in it, so when you run 98 on an E85 tune it would be 25% richer. Is that right? The other issue is that the timing for the E85 tune would most likely be too much for 98 fuel so some octane booster would help that part. But I think the car would be running so rich that it wouldnt matter. I believe the amount of fuel is the issue not the octane in that case.

Do you have any results of this? All the results I have seen from GTX3076 have been average. They had more peak power but also more lag.

Yup agree with everything you just said. can't see a problem with cleaning out the inside a bit.

A restrictive exhaust on a turbo car creates more lag and reduces top end so its just lose lose. For the sake of a few hundred dollars spent on modifying the exhaust could net considerable gains, I dont know I would just love to know. But why would hks create these dump pipes and why would all the front pipe manufacturers start them off smaller than 3" and then increase them to 3".

Woops I was trying to do it on my phone, try this one: http://cgi.ebay.com.au/APEXi-GT-Spec-Front-pipe-Skyline-R33-ECR33-RB25DET-/380277810553?pt=AU_Car_Parts_Accessories&hash=item588a52e579 See how the top part is a reduced diameter. I have pretty much decided just to use the dump pipe as is and buy a Blitz Front pipe. The provided dump pipe seems to work fine for everyone else.

Is it this apex front pipe: http://m.ebay.com.au/Pages/ViewItemPic.aspx?emvAD=320x411&aid=380277809380&emvcc=0 It looks to have a smaller diameter at the flange to the dump pipe.

haha what front pipe do you run joey?

Yeah mine is the same 2.75" flange but the internal diameter is smaller, bout 67mm.

Agreed the wastegate port size is excellent! It just seems strange to reduce it so quickly. You can't have too big of an exhaust behind a turbo its just whether the extra hassle is worth it. I know what you mean, hks got the turbo so right surely they can handle the respective dump pipe. Maybe I am putting too much thought into it, just want to do it once.

Thanks Dave no hurry. Also just wondering what your logic is behind the dump pipe having a diameter of 2.75" and then using a 3.5" catback, sure it won't hurt anything but I don't see the point.

Also interesting how almost all brand name front pipes have a 2.5" or 2.75" start to them and then turn to 3".

Thanks Dave you are a legend! Sorry for the slow reply just got back from Japan. The dump I have looks almost identical, yours looks like it has a 3rd pipe welded in but mine just has the 2 large pipes welded together. Also mine reduces down to a 2.5" size at the flange. The part that has me scratching my head is why would they funnel it down to 2.5"?? whats the point of having a big opening and funnelling it down to 2.5" and then expecting people to run 3" front pipes etc?? Surely the narrowest part of the exhaust is the restriction especially when its right near the front of the exhaust. I am thinking about getting an exhaust place to chop off the lower 2.5" part and join it with some 3" pipe so its never smaller then 3". What do you think?? It does seem to work fine without it (other results on this forum), it just seems strange. Even people with stock turbos try and keep the exhaust 3" turbo back! Are you sure yours is 2.75" inches at the flange? If so, I think mine will need some modifications.

Hi all, Can someone help out with the dimensions of a HKS 2835 Pro S dump pipe? The one we have is a split dump pipe, the main pipe being 2.5" and the wastegate pipe being 1", the wastegate pipe merges with the 2.5" pipe before the flange to the front pipe. 2.5" at the flange seems too small to me?? Help please!

In this case I would be either doing a lot of reading on here, or just find someones setup that you like and copy their setup and take it to the same tuner (obviously must be local to you and run an automatic gearbox).