Jump to content
SAU Community

Recommended Posts

sounds on the money to me. i wouldnt get your hopes up to much. any rb25 making close to 400kw on a gt35 is very stout. hell my 26 only made 376 on 25pound with a t04z...

i thought the t04z make big power on rb26's?

my rb26/30 is making 405awkw (equivalent to 445rwkw) on low mount garrett -10s @ only 23psi

Had a chat to Adam again tonight.

And he said the dump and new cooler would be the best place to start.

I asked how many cars he had tuned making 400+ with a 3 inch dump and he said none.

Not saying there are not engines out there doing this. But if he says he has not seen one then there must be a reason.

For the exhaust its a 5min test, pull the 02 sensor and fit a brass adapter and vac nipple, hook the second map sensor in to it and plot it.... bingo done.

i remember talking to rob @ rips about my exhaust which is a hks super dragger (starts @ 3.25" then goes to 3.75" at the rear).

his feedback "run it with the full exhaust then drop it at the front pipes, you will then know if your exhaust is choking any power"

^^^^ How do the above two posts address whether the dump is the issue....what you have described is usefull for determining whether you have backpressure in the exhaust....not whether you have the proper gas expansion off the turbine?

If you go back to my previous post with two excerpts I cut and posted...refer to the first one...now this guy had a 3 inch dump going to a 3.5 inch side pipe...now I doubt there would be any backpressure present in this system....yet his hp was falling over. He then fitted a 4 inch dump and 3.5 inch full street exhaust and abracabra he made more power everywhere.....and if you read his post weren't not talking massive hp figures here either.

For your convenience:

Dropped the exhaust, still with the 3 inch dump pipe tho, could run an extra 7 deg timing (up to 22) and made 450 at 24psi. Now this was ok, except when we added gas, Power would spike to 490 then as the CFM increased power would always drop back to around 450 rwhp. This was with a 3 inch dump pipe, then increasing to 3.5 inch and exiting out the side of the car. It didnt seem to matter what we did with camshaft timing or anything else for that matter power always fell over hard.

So off to the drag strip, did what we needed to do with the car...... Afterwards a new full street exhaust was made, with a 4 inch dump and a full 3.5 inch system. This thing now makes more over all horse power than before with a 3 inch dump and side pipe but now makes more horse power the harder we rev the engine. Everything here has been done with a screamer pipe, So you could imagine the added stress with CFM having it plumbed back in.

Edited by juggernaut1
...and replace the 4 inch body cat with a 5 inch body cat.

agree with that too.

juggernaut is on the right track. :( yes it's good to keep heat in the pipe to keep the energy in there and keep the gas velocity high BUT you also want to allow the gas to expand nice and quickly once it's past the turbo outlet. you need to for POWER!

^^^^ How do the above two posts address whether the dump is the issue....what you have described is usefull for determining whether you have backpressure in the exhaust....not whether you have the proper gas expansion off the turbine?

agreed i should have read the whole thread :P but depending on the type dump it can still be usefull, if it is a straight through pipe then no it is a useless test, but if it is a chamber type with the usual 3 bolt flange (and 02 sensor bung placement) it will still show up any restriction, even with the exhaust dropped. We just used this to sort a restriction in a s15 that had a dodgy china split dump, then tested the tomei and CES (tomei was the pick).

  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Put a fuel pressure gauge on it. Replace the turbos. Probably completely separate issues.
    • What copper washer do you guys use on the bleeder bolts? The existing one I have I had no idea where to find it in a local store, I did buy some online but that are only 1mm thick whereas my old one is 2mm+ thick and when I put the new washer out and squeeze the top radiator hose I can hear a bit of air but not with the old one. Does this matter? The new one doesn't leak, but the inner diameter is a bit loose whereas the old one threads on the bolt.
    • Howdy all, after being out a few weeks ago on a spirited drive in my GTR I have 2 issues that oddly have appeared at the same time. Whilst accelerating quickly through the gears all of a sudden i’ve lost power at the top of third gear (below redline around 6000rpm) for no obvious reason.    From that point onwards the car has been running rich on idle, won’t really rev under load without a ton of black smoke and the odd backfire, and dying as a pull up to a set of lights unless I keep the revs up around 1500rpm. In addition when shutting down the car that same night (I was 10 minutes from home) I noticed one of the turbos was significantly noisy on wind down when shutting off the engine. After letting the car cool down overnight it starts up fine, although once it gets to temp the revs start to creep up and down, the exhaust is darker than it should be and it also sounds like it’s running rich (fat note) I’ve put a new set of plugs in it - no change, the old plugs all seemed OK with two of them being somewhat richer/fueled up than the other 3 with 1 being borderline. I’ve smoked tested the intake system via the front of the Turbos, found a split vacuum hose going to the factory boost gauge sender, which I have since replaced.  Also found another leak on the gasket coming off the rear turbo outlet, have also replaced this. After fixing both of these leaks - still have the running rich issue. I’ve also tried another pair of AFM’s - no change here After pulling off the front turbo intake pipes, there is obvious shaft play in the front turbo, which now hisses loudly on light revvs although I can’t see why this would make the car run funny even under idle. I’m curious to know why it’s running rich before I potentially replace/rebuild turbos. The car is completely stock <50,000kms  other than an exhaust. Oil and coolant are all clear. I haven’t bothered with coil packs as it looks like they won’t be the issue due to condition of the plugs. Any help appreciated as I cry myself to sleep!
    • No probs at all. I used to love trying to dig up obscure info for those in need where possible going back 20+ years on SAU.  I did have another look and couldn't come up with any closer match. I'm leaning towards those skirts in your first pic are custom fitments, cut down/extended or from another car entirely and modded to fit an R34 sedan. I would've thought someone in Japan had them and taken a photo at some stage over the last 2 decades but there's nothing. Someone out there must know surely.
×
×
  • Create New...