Quick Dyno session today

[John Dixon]

Managed to get a quick trip to the dyno today to sort some running in mapping but unfortunately my clutch release bearing siezed on one of the run downs so had to cut the session short.Didn't even get any mapping done, just enough runs to establish 2 things really: First that the fuelling is still too rich but OK to run for now.Second that the airbox/intake hose combo I have is too restrictive. Didn't manage to isolate which part due to the problem above, very frustrating.Results so far, with air box lid on, ~350bhp. With lid off 420bhp @ 7.5k (on the current rev limit). Not too bad for such a rough, guesstimate tune, hopefully a bit more to come.I think I may have been a little conservative on the cams, at 2500rpm it's making 300ft-ibs

[DriftingisLame]

Man that is awesome, but how are you coming up with a BHP figure? This is on a chassis dyno is it not?

Good work!

-Max

[SuperHatch]

Man that is awesome, but how are you coming up with a BHP figure? This is on a chassis dyno is it not?

Good work!

-Max

Because the "b" is for British Horse Power, duh!

[elwesso]

its worth at least 10HP if you drive on the right hand side of the car

Pretty impressive numbers... 450HP should be EASY, maybe you'll be knockin on 500's doors... I would say most of that comes from the cams...?

What size injectors did you go with, if I recall you went with some top feeds.

[Bart]

Gee mate it sounds great. I can certainly live with that noise for a while.Yeah the air box does look restrictive, you could go for a twin plenum set up similar to what the straight 6 GTR's use. (but the GTR uses a single plenum of course) kind of imagine 2 GTR plenums with 4 intake tubes on each side.

[Mettler]

Gee mate it sounds great. I can certainly live with that noise for a while.Yeah the air box does look restrictive, you could go for a twin plenum set up similar to what the straight 6 GTR's use. (but the GTR uses a single plenum of course) kind of imagine 2 GTR plenums with 4 intake tubes on each side.

Have you seen the factory intake setup on a Nissan Pulsar GTIR? It's pretty much like that too... (but obviously sized for boost) You'd build a setup like this much with a wider plenum to fit between the V. Check out these pics:



Then I remembered the Corvette LT5 engine and this engine's intake design wouldn't work too badly designed for ITBs:

[Bart]

Nice thanks for reminding me, the GTiR would be a good start but the Corvette style plenum would be ideal for John to clear the hood/bonet

[Carl H]

bhp = brake hp = crank hp.impressive numbers none the less.

[John Dixon]

The injectors are Bosch 440cc top feeds (type 3 multi jet).

Yes, it's crank HP, I never quote wheel HP, it's meaningless. Changing tyre pressures, running in different gears, strapping the car down harder can all change the wheel HP figure significantly but if you do coast down properly you'll always get the same crank hp figure.

Cheers for the pics on the intakes. I'm actually going for something similar to either the LT5 pic or the VG30DETT setup depending on what intake lengths turn out to work best. I'll change it all when the new 52mm throttles go on. I'm hoping most of the restriction turns out to be in the 2.5" ducting feeding the box as there is a resonable x-section area inside the box its self.

[Carl H]

i had been told in past that the plenum of the engine should always be double the engine's displacement...dunno how true that is with ITBs tho.

[Aus450zx]

but how can they k

Yes, it's crank HP, I never quote wheel HP, it's meaningless. Changing tyre pressures, running in different gears, strapping the car down harder can all change the wheel HP figure significantly but if you do coast down properly you'll always get the same crank hp figure.

but how do you calculate what is being lost through the drivetrain? the measurement is still being done at the wheels...

[John Dixon]

but how do you calculate what is being lost through the drivetrain? the measurement is still being done at the wheels...

Declutch, measure coast-down loss then add to the wheels figure to get flywheel. The dyno guy that operates the one I use has run many engines on an engine dyno then installed them in cars and run them on the chassis dyno. The numbers always come out close.

[jbrobatl]

what compression ratio are you running? when are you going to fix things and get it back on the dyno?

[John Dixon]

CR is 12:1.Hopefully soon, just never have time at the moment!Also discovered the VTC was not switching so that should lift the top end a bit too when I get it fixed.