dyno run today with the car prepped as requested by my tuner(kempower in zolder/belgium) as follows: jwt single POP, mongoose,gassed up with 98 octane fuel.

result : from 273 to 335 hp on 14 psi boost.

what a failure!!!

this means that my otherwise smooth running ,well-behaving, non- smoking- and- free- of -suspicious- engine- behavior- TT had only some 250 hp in stock condition!!!

Where did these 30 ponies run-off to ?

 

before you start saying anything: I trust this tuner with my life,he has a solid reputation and he's done another car of mine , a 200sx s14 and it went from 200 to 245 hp...without induction kit or free exhaust, just bone stock!!

 

Now,what could be wrong with my car?

 

Some info first:

 

*fuel is indeed 98 oct, but from a cheap source; this could give quite some loss.

 

*the exhaust line is enormously restrictive "somewhere",he said, and he mistrusted the exhaust a bit.

I said the mongoose is sold as fully freed up ( confirmed solemny again by collins performance, for what it is worth) .

I know that it is not as good as HKS or the likes, but it should be better than stock, right?

 

I suggested a dysfunction of the cat system, which he didn't have the time to measure today.

 

* he did a nissan consult test, and no error codes were noted.

 

*I had my cam belt changed recently at a small nissan dealer.

could the tech guy there have the cam pulleys a tad out of position?

this could mean the loss of some 10% power.

(also motor oil new and fully synthetic, also synthetic oil in gearbox and diff., new plugs )

 

* the only thing I do not know is the compression test.

 

 

 

but anyway , what we will do now is completely decat(=pre and main) as he suspects a major blocking in this area( or else the mongoose is really worth nothing)

I hope this will liberate some 30 hp but I will still be some other 30 short from what it should be.

I will let him check compression and camshaft pulley position too.

 

I am in dire need of some advice here people !!

Cheers

Rik

Belgium

 

PS: sadly , TT.net is down partially now so I cannot check an article called " pepping up your higher mileage 300". It involved renewing some fuel (pressure?) sensors and two other small valves somewhere...

Does anyone know about this article?

I think a stock zed puts 280 at the cracnk and 240-250 at the wheels,

 

I don't know what other guys run at 14psi though

henri - you say that you are running 14PSI. Is that with an upgraded chip or not?

 

If you are running higher boost with the standard chip, you may have fuel delivery problems due to the standard chip having a leaner mapping.

 

There have been reports from people on the forum that after decating, they have noticed the turbos spooling up sooner, more power but on the downside, the turbos have started smoking a little more frequently. If you turbos are in good nick, you shouldnt have a problem.

 

Back boxes are also a consideration.

 

I dont know what you are using to measure your boost but I wouldnt believe the stock gauge.

 

Just a thought!

If those are rear wheel numbers then they look OK to me.

 

Speaking from experience ...

 

Mongoose exhaust is fine - it won't be causing you a problem.

 

Unless you have something actually wrong with your cats, then you're not going to release bhp by getting rid of them.

 

I think the chip question is an important one. Also - are you running an auto or a manual ?

if thats at the wheels then i dont think its that far of.

its actually about right.

more details on car?

Auto - Manual?

what year as if it has precats you could gain there.

but add between 12-15% on drivetrain loss if that figure was at the wheels

the car is a 90 manual.

the power quoted is at the flywheel.

the chip is actually a whole piggybacked ECU, with more options available than a simple chip.

could there be severe power loss due to heat soaking and insufficient intercooler cooling on the rolling road?

 

rik

then your figures are down.

you could have been heat soaked.

Intercoolers would help :D

Anyone fancy another group buy :D

What ECU? management system are you running? That could be alarge part of it.

I would

A: check for boost leaks ect

B: try different fuel

C: Decat car?

D: make sure the turbos are fine?

E: buy my intercoolers lol :D

F: check plugs(you have doen this no)?

G: Do compression check ect.

 

FYI : Stock car should make anywhere from 225-250 on the back wheels. Drivetrain loss is anywhere from 12-15% from my understanding.

Also, what gearbox do you have and how was the drivetrain loss calculated ? What was the rear wheel figure ?

captain,

1.about ecu type; I don't know , but it is the box was taken out of my 200sx auto '94 that had 240ps instead of 200ps and 370Nm torque instead of 270Nm. The 200sx was bone stock: no induction or exhaust improvement.Never had any engine damage over the next 70k miles and fuel consumption even a tad lower with this ecu.

The rolling road used is also the same.

 

So I daresay the ecu does what is is supposed to do.

 

2.better fuel will be used for next test for sure.

3.the tuner reported 0,00% boost loss, so that certainly not the problem

4.turbo pressure remained nicely at 14psi with no sign of weakening until redline, so I suppose they are ok too

5.plugs are stock warmth but brand new

6. compression check will be done soon

7. heatsoaking: could not have been the problem with two big fans aimed at the IC's, says tuner...

 

 

hairsy,

 

the drive train losses are calculated automatically by the rolling road, so I do not have any "at the wheels" figures.

(The car is a manual.)

I would guess that the losses are calculated then by measuring the friction in the drivetrain after releasing the accelerator. The rolling road should be able to provide a wheel figure though and it's worth getting this. No flywheel figure can be precise unless it's taken with the engine on a bench.

 

See if you can get a rear wheel figure. You can then compare it to what the guys on here got at the rolling road day earlier this year. You may not be too bad.

 

Don't be disappointed - at least you don't drive a diesel like me

Originally posted by Hairsy

I would guess that the losses are calculated then by measuring the friction in the drivetrain after releasing the accelerator.

 

This sounds really interesting. Can you actually approximate transmission losses with everything still in place on the car? I can imagine on a manual that, with the clutch held in, you could externally accelerate/decelerate the driven wheels and note the resistance. Does this sound plausible?

... estimated flywheel figures are a waste of time. In my book unless it touches the road it doesn't count.

 

Peace !

Originally posted by AndyP

... estimated flywheel figures are a waste of time. In my book unless it touches the road it doesn't count.

 

Peace !

exactly

flywheel figures are there to just bump up what you dont have lmao.

it is a pointless figure as in the real world it is not used.

what goes down to the road via the actuall wheels are what matters period.

Originally posted by Mike Duffy

This sounds really interesting. Can you actually approximate transmission losses with everything still in place on the car? I can imagine on a manual that, with the clutch held in, you could externally accelerate/decelerate the driven wheels and note the resistance. Does this sound plausible?

 

The rolling road which mine was done on kept measuring after the power run and the graph showed negative power after lift off, as it measured the drag of the drive train.

 

My opinin (for what it's worth !) is that if the machine is doing this, then it's almost certainly going to give a greater drag / loss than reality. My reasoning is that, in addition to true transmission loss, it will include the friction in the engine itself (e.g. rings on the bores) and these are occuring before the flywheel.

 

Only a theory though. Anyone else got any ideas ?!

Originally posted by Hairsy

The rolling road which mine was done on kept measuring after the power run and the graph showed negative power after lift off, as it measured the drag of the drive train.

 

My opinin (for what it's worth !) is that if the machine is doing this, then it's almost certainly going to give a greater drag / loss than reality. My reasoning is that, in addition to true transmission loss, it will include the friction in the engine itself (e.g. rings on the bores) and these are occuring before the flywheel.

 

Only a theory though. Anyone else got any ideas ?!

I'd say the engine would give one hell of a lot more drag than the transmission components. That's why I mentioned putting the clutch in. Surely this would give just the transmission drag (minus the clutch pressure plate).

 

As always, please note I don't know what I'm talking about!

Yes, sounds good to me.

 

Mine was an auto but I guess it could have been stuck into neutral.

 

It's never going to be exact but I reckon your idea is gonna be as accurate as you're gonna get. And not a million miles away ...

 

I'm interested in the fact that the rolling road that Henri was using didn't give a rear wheel figure. I've never heard of that before. Would love to know what calculation method it uses.

 

Henri, any chance of finding out ?

hairsy,

I will call upon the guy tomorrow and ask him some details about the rolling road and calculation methods it uses.

Will post the answers tomorrow afternoon.

 

rik

Cheers !