Can't seem to get enough power out of built RB25DET?

[radianation]

I have a rebuilt rb25det and can't seem to get over about 386 rwhp on a dyno-dynamics dyno.

Basic setup details:

rebuilt engine w/20 overwiseco forged pistonseagle rodsport & polish head1.1mm cometic hgarp main studs & head studsfactory cams, valves, springs, crankgreddy intake plenum850cc denso injectorslovefab top mount exhaust manifoldBullseye Turbo S362 HKS SSQV BOV, HKS GT-II 60mm WG3" turbo back exhaust

I also have AEM EMS and HKS EVC IV. The AEM EMS has been professionally dyno tuned twice.

There are a lot of other upgrades, but I think these are the important ones for my current issue of power.

My target power goal was 550rhwp. The car drives great and I should be more than pleased with the current results, but I can't help but feel like I've invested time and money into achieving my power goals and have come up short. At 386rwhp I don't think I would have technically needed to go with forged pistons and eagle rods, for example.

The same turbo makes 600rwhp on my cousins 2JZ with the same amount of boost. Speaking of which, I'm running about 18lbs of boost on 93 octane pump gas. I could go with 22lbs pretty easily, but I'm still short of my power goal with this calculation.

Any help is greatly appreciated. I have considered upgrading the camshafts and valves/springs, but it still feels like something is off with this setup and I'd like to solve that before upgrading more components if that is an option.

[ItzGenX]

New cams should open her up good. The thing is your numbers seem a bit on the short side still, even for stock cams. Your timing may be set too much on the conservative side. There are many RB25s over that power level in the 400whp+ on about the same boost level without overworking the turbo. The difference would probably be cams vs other people's setup, but I wouldn't rule them out as a possible reason why you are so low.

[radianation]

I would not be surprised if the timing is a potential culprit. It's known to be fairly conservative.

[Cjmartz2k]

What do your exhaust temps look like? Who tuned it?

[radianation]

Spek EGT reads around 9 on average. Autolab in Louisville, KY tuned it on a dynodynamics. I have been doing the "tuning" since.

[eh?]

Did you ever get that base timing set correctly?

[Cjmartz2k]

900c or F?

[radianation]

900F and I sure hope I got the base timing set correctly, but I haven't been able to have anybody look over the setup to make sure I did everything right. It drives fine though.

[gawdzilla]

where is your sensor? 900F is super super low for a WOT EGT.

your number is not that far off. 400 whp on a dyno dynamics @ 18 psi seems healthy to me on a turbo of that size. the s362 is similar to a gt35r, no? keep turning up the boost and push it more. you cannot compare "psi to psi" to a different motor like that. you can try pushing the timing more to squeeze out some hp, but 400 is not terrible for 18 psi, especially through that dyno. keep in mind that a lot of people with high dyno numbers on their RBs are running bigger turbos. your compression ratio might also be lower with the wisecos.

[flatrate]

if you have a Flex section in your exhuast make sure its not collapsed, ive seen this happen mutiple times

Are you running a chambered muffler?

make sure your cam timing is correct..

check for boost leaks

you have a dyno graph you could post up so we can look at it?

[radianation]

EGT is located in the downpipe. If I'm driving on the hwy at 70mph for 15-20 minutes solid it will increase to about 11 at most and stay there. The 900F reading is just what I see daily going to and from work.

I was playing with the timing again just now and I think I missed a critical step a long time ago in zeroing out my timing map temporarily while I match things up. I just can't remember what I did because it's been so long ago. Frustrating.

[flatrate]

well what you have highlighted there is just base timing/idle, you look to be running alot of timing around where your peak power is 27 degrees at 18psi (124ish KPA) are you sure its not pinging or your having any detonation issues thats alot of timing for that boost level... maybe RB's are different but seems like alot...

You need to talk to eh? he has EMS and seems to know his way around AEM he has his map posted on the RBforums.net he made 420ish wheel on i think 14.5psi

Not to mention your map looks very untuned i dont think the tuner knows whats going on... IMO

[radianation]

The reason I started tuning it myself (slowly) is because the tuner told me he could not find the timing marks so he didn't adjust the timing. Well, that's bogus because I was able to see the timing marks the very first time I used a timing light.

I would not be surprised if the timing is screwed up because all he messed with (mainly) was the fuel map.

This timing map is either from the startup or was implemented by the first person who helped tune the car (and I thought he just used the base map and sent me on my way)...

I am willing to learn but need help to get there, or I need somebody who comes recommended for tuning the RB and can work with me to get the results this car is capable of doing.

I do not believe there is any pinging.

[radianation]

well what you have highlighted there is just base timing/idle,

Yes, this is an older screenshot taken when talking about idle timing so the caption is referencing that. I just linked it up because it is still the same timing map I have right now.

[240slidekat]

make sure you have the timing sync on aem. sounds like your a little bit retard on your timing. it should be under ecu set up.

[QUOTE=radianation]The reason I started tuning it myself (slowly) is because the tuner told me he could not find the timing marks so he didn't adjust the timing. Well, that's bogus because I was able to see the timing marks the very first time I used a timing light.

I would not be surprised if the timing is screwed up because all he messed with (mainly) was the fuel map. QUOTE]

he should not even tune it unless he gets the timing synced first. it could potentially mess up your engine.

[flatrate]

yeah if the timings not syncd who knows what it really is

[74260zt]

I have a feeling, getting the timing correct, will wake that bad boy up....

I don't have any current screen shots of my timing map, but this is close.

CLICK 3 times to enlarge
Modified by 74260zt at 7:16 PM 12/27/2009

[radianation]

Ok. I've made a post on the AEM forum as well, but here are the parts that I want to clarify about setting the base timing on the AEM/RB:

1. I have not done anything physically to the CAS to adjust timing. It's dynamic and the AEM just syncs with it, right?

2. I've adjusted the timing coarse/fine with the AEM and used a timing light, but when I did this I did not temporarily 0 out my timing map so I think it was skewed.

My question is, when using the timing light and adjusting the coarse/fine on the AEM it says to make them match, but I wasn't able to make them match. I just adjusted the AEM so that the timing light showed the marks lined up at 15 degrees. =/

[spolitte]

^^^ Agreed (with flatrate that is), If your timing sync numbers with the AEM unit aren't good then you might need to replace the CAS wheel with the one that AEM sends you if you haven't already done so. And if the timing sync isn't good then he definately should not be messing with fuel maps or any other tuning maps for that matter because your timing may be WAY off and might blow up the engine

[flatrate]

Yeah hes running about 6 degrees less timing than what you have in your map, granted setups are different but 7 degrees is a huge difference... figure it out and report back

[240slidekat]

Ok. I've made a post on the AEM forum as well, but here are the parts that I want to clarify about setting the base timing on the AEM/RB:

1. I have not done anything physically to the CAS to adjust timing. It's dynamic and the AEM just syncs with it, right?

2. I've adjusted the timing coarse/fine with the AEM and used a timing light, but when I did this I did not temporarily 0 out my timing map so I think it was skewed.

My question is, when using the timing light and adjusting the coarse/fine on the AEM it says to make them match, but I wasn't able to make them match. I just adjusted the AEM so that the timing light showed the marks lined up at 15 degrees. =/

okay first you dont have to touch the CAS and here is an "easy way to sync the timing"

1. hook up timing light2. go to the ecu set up > set timing blah blah blah3. put a value at the "fixed timing" section (i entered "10" degrees)4. check your timing with the timing light and make sure its the same value you put in under fixed timing5. if it is not then use the advance/retard buttons to get it to the same value (10 degrees).6. once you match the fixed value on the aem ems and the value on the timing light then your done.

hope this helps, im also using aem ems so if you have anymore question then feel free to ask me. i know that aem ems is a pain in the butt sometimes.

[bobob729]

this all honestly sounds like a timing thing do what he^^^^said my haltech is the same way so...... also i don't want to thread jack but how fast does your turbo spool cause i'm looking into getting the same one but want to know how quick it spools or if there is alot of lag?

[radianation]

The turbo spools reasonably fast considering the size. When I do autocross if the track is really "twisty" then I have a hard time keeping the turbo up, but on avg courses I can get in boost a lot and stay in it (2nd gear). I'd say by 3,500 it's spooling nicely and 4,000 you better hold on. I'd like to have it kick a little sooner to be honest. =/

[bobob729]

so you hit full boost by when?

[eh?]

It's hard to diagnose these kinda problems over the internet so do this:Log a 3 gear run from 3000-rpm to redline and post it up. Make sure you keep your foot all the way down.I can see in your dyno graph something happened at 4900rpm. Are you running 18 psi all the way to redline?

[robbie2883]

as was said the numbers are not that far off....keep in mind a dyno dynamics dyno is one of te lowest reading dyno's out there. you would see a 18-25% gain in numbers by just slapping the car onto a dynojet.

[radianation]

so you hit full boost by when?

From the dyno I'd say about 4,900rpm ?

[radianation]

It's hard to diagnose these kinda problems over the internet so do this:Log a 3 gear run from 3000-rpm to redline and post it up. Make sure you keep your foot all the way down.I can see in your dyno graph something happened at 4900rpm. Are you running 18 psi all the way to redline?

There was something strange going on with that last dyno pull that never made sense. Boost was limited @ 17psi for some reason even though the boost controller was set for 22psi. I have no idea what the guy was doing. Also, the redline was limited to like 6700 rpm.

Those two items combined with the timing adjustments that might be required and the DynoDynamics low-scoring factor could be all that's required to get it higher?

[240z4u]

You should be running at least a 1 bar spring, else the boost controller will be unable to keep the wastegate shut. I had that happen on the dyno once.

[eh?]

There was something strange going on with that last dyno pull that never made sense. Boost was limited @ 17psi for some reason even though the boost controller was set for 22psi. I have no idea what the guy was doing. Also, the redline was limited to like 6700 rpm.

Those two items combined with the timing adjustments that might be required and the DynoDynamics low-scoring factor could be all that's required to get it higher?

Possibly, though just raising your rpm wont do anything until you get the real problem resolved. You can see the hp leveled off after 6100 rpm which is weird. Going on a dynojet will net you more but wont resolve your power leveling out. You need to log a run, so boost and timing can be seen.