SC500 down on power cam?

[wycoller]

My SC500 Griff has never developed 400bhp plus that even 450SC chimps and other 500 are developing.
All gurus and Colin Harvey point to cam to much overlap
My question is RR showed fuel air ratio about 12:1-14:1 which told okay this reading above 3000rpm open loop on lambda,s
if i am loosing boost through excessive overlap should the RR show running rich
as data from AFM will not know if loosing some air vol,due to excess overlap and chipm is MA mapped to standard cam etc
am i missing something?
cheers jim

[spend]

wycoller said:

All gurus and Colin Harvey point to cam to much overlap

Funnily enough I've heard Forced Induction gurus dispute claims that wild cams and high compression are detrimental to performance. (maybe too much performance would cause the best kind of catastrophic consequences though )

If you believe them you would have to think something else is not working properly to cause such a difference?

Simple things like checking 8 header temps, vacuum gauge on the plenum, fuel pressure gauge, timing light.. I'd suppose.

[wycoller]

spend said:

wycoller said:

All gurus and Colin Harvey point to cam to much overlap

Funnily enough I've heard Forced Induction gurus dispute claims that wild cams and high compression are detrimental to performance. (maybe too much performance would cause the best kind of catastrophic consequences though )

If you believe them you would have to think something else is not working properly to cause such a difference?

Simple things like checking 8 header temps, vacuum gauge on the plenum, fuel pressure gauge, timing light.. I'd suppose.

all basics check out okay, wild cams kind off defeat object of FI however cam design does influence performance in forced induction for eg opening exh v/v earlier in turbo-charging to enhance turbo performance, but i,m going back 20 yrs on my engine design etc things probably moved on since as haven,t kept up
if i am loosing charge on overlap would be one explanation why it would appear my exh manifolds appear to be 'relatively cooler" not reat scientific like as no data other than how hot it feels under the bonnet after a good run out
funny how easy it is to monitor engine performance when you can wander down check firing, and comp pressures and constant feedback on eng temps etc fiddling with motors especially like the old cloth hat brigade eg harry ratcliffe without lap tops etc could tune and set up engines

[450Nick]

Hmm if you can measure yours somehow, I'm running an EGT sensor on port 5 (hottest) on my SC450 through the Emerald. I could probably tell you how hot its getting under load if you like? You'd obviously need to be able to measure yours somehow as well though to have some comparisson?

My SC450 is making just over 400 but I'm doing that with ACT trumpets, induction, MC1 cam, larger charger, smaller (85mm boost pulley), full ACT decat sports exhaust and an Emerald so perhaps you're not that far off?

[Pasco]

I thought Hamish's motor was doing around 450bhp nick

[450Nick]

His will make more than that when he's turned it up! Mine will happily sail past tuned Cerbs/Sags etc (the best was a very healthy 4L Sag with close ratio box & trick diff during a drag race up the main straight of Cadwell Park - the Sag was NOWHERE!). I've also checked the power using my DL1 race datalogger with all coefficients + weight added in and it comes out with about 400 also (402 IIRC) so I'm pretty certain its correct!

Edited by 450Nick on Tuesday 18th May 17:51

[Bluebottle]

Mine has been of three different rolling roads to date and its slipped on every one of them The last time was last month at Mech Repairs and it was too powerful to do a power run on their rollers (was using them to check mapping and some fault diagnosis)
So its been a best guess to date, its certainly well north of 420 bhp, although at the moment its making precisely zero bhp due to the valve guides on the NEW engine being fubar

Edited by Bluebottle on Tuesday 18th May 18:12

[hiltonig]

what valve guides have you gone for ??, phosphor bronze or the steel sintered guides ???

Edited by hiltonig on Tuesday 18th May 18:23

[wycoller]

450Nick said:

Hmm if you can measure yours somehow, I'm running an EGT sensor on port 5 (hottest) on my SC450 through the Emerald. I could probably tell you how hot its getting under load if you like? You'd obviously need to be able to measure yours somehow as well though to have some comparisson?

My SC450 is making just over 400 but I'm doing that with ACT trumpets, induction, MC1 cam, larger charger, smaller (85mm boost pulley), full ACT decat sports exhaust and an Emerald so perhaps you're not that far off?

I have mod trumpets act induction 72mm throttle body , larger charger smaller pulley and single Cone air KN filter rated for 400plus as couldn,t get duplex filter in behind my light pod, as far as concerned plenty out Hamish reckons its the cam but beleive my questions are valid if it was the cam due to excessive overlap etc?
so my performance isn,t that impressive as what everyone else is raving about!!!!!

[wycoller]

450Nick said:

Hmm if you can measure yours somehow, I'm running an EGT sensor on port 5 (hottest) on my SC450 through the Emerald. I could probably tell you how hot its getting under load if you like? You'd obviously need to be able to measure yours somehow as well though to have some comparisson?

My SC450 is making just over 400 but I'm doing that with ACT trumpets, induction, MC1 cam, larger charger, smaller (85mm boost pulley), full ACT decat sports exhaust and an Emerald so perhaps you're not that far off?

what boost you running on Colin reckons 6-7psi max on standard engine without doing a Hamish
and going for JE special

[450Nick]

Not sure on mine, I think around 7-8? Thats a bit of a guess though as I never look at the boost gauge when on the beans. You can get away with it a bit more on the 450 as the compression ratio is only 9.35:1 as opposed to 10:1 for the 400s and 500s..

Yeah I'd suspect your cam probably... What injectors are you running? And what exhaust?

[wycoller]

450Nick said:

Not sure on mine, I think around 7-8? Thats a bit of a guess though as I never look at the boost gauge when on the beans. You can get away with it a bit more on the 450 as the compression ratio is only 9.35:1 as opposed to 10:1 for the 400s and 500s..

Yeah I'd suspect your cam probably... What injectors are you running? And what exhaust?

Exh de cat y SportsSS from Y piece to aft. Injectors cannot remember spec but i got from Colin full package to give me 400bhp plus on 450 you,ve probably also got a stronger eng are they cross bolted as standard or am i blowing bubbles, I.ll prob piss some 500 owners off giving cred to 450 eng
Anyway i,m in Houston so having Ian at tvR check cam etc like i said t****r at R** will not respond and give me details what goes round comes round word gets around

[450Nick]

Hmm must be something simple then... You've got the air, you've got the fuel, and the gas isn't restricted getting out so you should be making the power. The only reason it wouldn't was if the bang wasn't happening properly, so I guess check the cylinder compression and the cam... Not much else it could be other than dodgy timing?

[wycoller]

450Nick said:

Hmm must be something simple then... You've got the air, you've got the fuel, and the gas isn't restricted getting out so you should be making the power. The only reason it wouldn't was if the bang wasn't happening properly, so I guess check the cylinder compression and the cam... Not much else it could be other than dodgy timing?

Yes Cylinder comp was checked when i bought car all around 150 so doing leak down test burns about ltr every 7-800 miles so some wear on eng. I am looking at serious loss power around 10-12% on your figures, ignition timing is okay she runs quite sweet slight shunting now and then at very very light throttle and only now and then point is a good standard Griff is there with me up to about 60-70mph, maybe its my weight 320ilbs that takes edge off also need to do RR were they bolt straight onto axle tother end is connected ta "bailing machine or thresher with a large Leather Belt.

[wycoller]

450Nick said:

Hmm must be something simple then... You've got the air, you've got the fuel, and the gas isn't restricted getting out so you should be making the power. The only reason it wouldn't was if the bang wasn't happening properly, so I guess check the cylinder compression and the cam... Not much else it could be other than dodgy timing?

Yes Cylinder comp was checked when i bought car all around 150 so doing leak down test burns about ltr every 7-800 miles so some wear on eng. I am looking at serious loss power around 10-12% on your figures, ignition timing is okay she runs quite sweet slight shunting now and then at very very light throttle and only now and then point is a good standard Griff is there with me up to about 60-70mph, maybe its my weight 320ilbs that takes edge off also need to do RR were they bolt straight onto axle tother end is connected ta "bailing machine or thresher with a large Leather Belt.

[spend]

What injectors, at overlap the fuel overflowing into the exhaust might be skewing your AFR readings. I'd rather trust reading the plugs, ie pull them directly after a power run.

[wycoller]

spend said:

What injectors, at overlap the fuel overflowing into the exhaust might be skewing your AFR readings. I'd rather trust reading the plugs, ie pull them directly after a power run.

Dave
i,m a diesel man ( dirty word) fill me in there should be no fueling during overlap period) i,d thought injection taking place after this period, obviously not or you wouldn,t be making such statement I need to read up on things, okay mouth full of Popeye chicken and good ol boy biscuits (scones to us) I am all ears!

[spend]

Your injection is not timed into the cycle, just a 'timed' dosage if thats what you mean.

[v8 racing]

cam overlap on a mechanical driven blower wont affect outright horseblower, you may loose fuel economy and torque in the lower rpm range but not peak horsepower, the cam if you are going to have one ground is more like a n/a engine than a turbo or nitrous cam. you will of course loose power if the cam is worn which wont show up on a compresion test if it is an exhaust lobe that has worn

[Bluebottle]

I note from your post you have a different single filter intake setup. Can't recall if i've asked you the question before, but did you or have you monitored the peak boost either on or off the r/r?
Peak boost with a centrifugal charger is very sensitive to restrictive air flow. My initial setup lost 30% peak boost with one filter which is why the kit now has a twin filter setup.