Dyno Chart Full Of Fail - Please Help

[jet_r31]

Who idea was the reverse staggered cams

Cheers

Darren

[djr81]

Who idea was the reverse staggered cams

Cheers

Darren

What do you mean by reverse staggered?

Tomei (For want of a different option) offer the following:

Poncam A :260 inlet and 252 exhaust at 9.15mm lift.

Poncam B: 260 inlet and 260 exhaust at 9.15mm lift.

I have a 256 inlet and a 252 exhaust.

Upgrade option on the inlet side appear to be to go an extra 4 degrees and more lift picking one of 9.15, 10.25 and 10.80.

On the exhaust side the increments are in four degrees also although I didn’t look at the lift.

Inlet 256 degree 9.25mm lift. Opens TDC. Closes 41 degrees ABDC. For 221 degrees duration at 50 thou valve lift.

Inlet 260 degrees 9.15mm lift. Opens 1 degree ATDC. Closes 43 degrees ABDC. For 222 degrees duration at 50 thou valve lift.

Inlet 260 degrees 10.25 lift. Opens TDC. Closes 43 degrees ABDC for 223 degrees duration at 50 thou valve lift.

Inlet 260 degrees 10.80 lift. Opens 1 degree BTDC. Closes 41 degrees ABDC for 222 degrees duration at 50 thou valve lift.

Exhaust 252 degrees 9.15mm lift. Opens 42 degrees BBDC. Closes 8 degrees BTDC for 214 degrees duration at 50 thou valve lift.

Exhaust 256 degrees 9.25mm lift. Opens 46 degrees BBDC. Closes 7 degrees BTDC for 219 degrees duration at 50 thou valve lift.

Exhaust 260 degrees 9.15mm lift. Opens 47 degrees BBDC. Closes 3 degrees BTDC for 224 degrees duration at 50 thou valve lift.

[Dale FZ1]

Collapsed mufflers, cat....

This seems the obvious and first area to check. But there seems to have been a lot of effort concentrated on boost control and cam timing. This brought about bottom end improvements, pointing to decent outcomes. Then comments/suggestions drift quickly into using bigger cams which are effectively going to simply shift the curves to the right and sacrifice low/mid range.

The original point of the thread was a reasonably low peak power number for the general engine spec.

The torque curves shown in this thread show something that hits a peak and then just falls away.

Troy's suggestion is where the investigation and power hunt should have started, and does not appear to have been addressed. Disregard whether its a quiet or loud exhaust system. Eliminate the muffler/s and cat, do a trial run on the dyno and establish for certain just how much they are holding things back. Low cost, low effort test. And you can then make an informed decision on what to do.

Many instances where old/collapsing cat/mufflers are choking flow, and also where there are hidden neck-downs to quieten down flash name brand Jap exhaust systems.

[r32-25t]

This^^ you need to be looking at other areas, the cams are not going to be your issue,

Start with the exhaust, boost leaks, a stuffed sensor

[djr81]

A stuffed what sensor?

I doubt it is a leak based on it making boost. Anyone got a Z32 afm conversion for mv to airflow as I can read that off the power FC controller.

Edited August 13, 2015 by djr81

[infamous_t]

(New) result seems fine to me, he's not on e85 and it's a conservative boost level with cams geared at response over power.

My results are similar boost but on 260/260 + e85/hub dyno and your 70hp ahead at 4000rpm, but only 40hp behind at peak power.

Throw some more boost and some jungle juice if your chasing more outright power IMO

[djr81]

(New) result seems fine to me, he's not on e85 and it's a conservative boost level with cams geared at response over power.

My results are similar boost but on 260/260 + e85/hub dyno and your 70hp ahead at 4000rpm, but only 40hp behind at peak power.

Throw some more boost and some jungle juice if your chasing more outright power IMO

Cams are actually set to chase powahs.

Wish I could get a chart of yours on 98 but nevermind.

Not sure how much more boost there is the controller is at 82% or thereabouts something just over 20lb.

[r32-25t]

A stuffed what sensor?

air temp, crank angle, knock sensors

[Hadouken]

I made the same as you did on 98 at 18psi with smaller turbos and standard cams.

[GTRPSI]

Our R32 GTR had lost power before we pulled it off the road for a new engine build.

The other night i was dropping the exhaust system to remove the rear heat shields so i could drill holes to bolt a battery box down in the boot area.

Center muffler was collapsed, it was a 3.5" system, clogged down to a 2" (or less) system.......never would have guessed it without looking.

[infamous_t]

I made the same as you did on 98 at 18psi with smaller turbos and standard cams.

Do you have a dyno sheet to share?

The one in your build shows less power @ more boost compared to djr81s 2nd dyno sheet.

[r32-25t]

6kw (10hp) difference is f**k all and between a -9 and a -5 setup there should be a lot more then that,

As for cams being "too small" if someone can use a 260° in a 3.2 and make 475kw (645hp) why do you need bigger in a 2.6 when you aren't even making 375kw (500hp) yet

As has been said by multiple people, give up on cams and look else where

[djr81]

I dunno maybe a 32 has a very slightly longer stroke than a 26 and therefore doesnt need a long duration cam.

What I am trying to reconcile is the following (In no particular order).

Why the thing appears to have so much torque in the midrange when the -5 turbos arent known for this.

If the exhaust is collapsed (And yes at some stage I will get it checked) how does this fit up with it holding the 20lb boost in the top end - would it not struggle there?

How to differentiate between the theoretical changes for each of the cams, so what would a larger inlet do in this circumstance in isolation. Same question for the exhaust cam.

[SimonR32]

Really stupid question, are you sure they are -5's?

[Hadouken]

Do you have a dyno sheet to share?

The one in your build shows less power @ more boost compared to djr81s 2nd dyno sheet.

Oops must have been e85 results. Haha

But here you go for direct comparo. He says around 20 pound and this was 20 pound 98 and 3 years ago.

Cam Gears in and dialled up

Blue line before, Green line after

Hence why I say get it on a dyno. If he has -5's on a built motor then stop messing around.

[djr81]

Really stupid question, are you sure they are -5's?

Will go and have a look now that you have made me paranoid.

[r32-25t]

Really stupid question, are you sure they are -5's?

i was thinking the same thing