The V8 Owners Forum -

Just wondering if anyone would like to take a stab at some BHP figures Its over at Motorscope this week where they will be running it on there new Dastec rolling road, I reckon just short of 300 bhp
Spec;
5.0 litre with off set ground 86.36 crank, forged 96mm pistons, steel h section rods, stg4 big valve heads, h404 cam kit, 10.5-1 compression ratio, fully dyno tested and run in.
cloyes chain and gears
adj pushrods
steel rockers
crane hi rev lifters
Quad Weber 48 DCO/SP’s
John Eales manifolds
helix motorsport clutch
lightened flywheel
Powerlite Starter motor (RAC 318)
oil cooler (Stainless Braided oil lines)
Mallory unilite, promaster coil, HyFire ignition
Custom full Stainless Steel exhaust system by: Zorstec
Primary length: 20",
Primary ID: 1 5/8".
Secondary length: 10".
Secondary ID: 1 7/8",
Tail pipe: 3"
Magnecor R100 (10mm) HT Leads
S-Plugs: BCP 7RVX

Should be over 300 with those parts, with a bit of luck.
It's a very similar spec to my new engine.

I reckon well over 300! I spoke to John Eales about my 4.6 and Sir Eales regilary gets over 300 with a 4.6 using quite mild cams so you should sail over 300.

Hopfully over 300 just thinking that the long inlet manifolds might be a limiting factor regarding peak BHP this was a view of Jon Wolf (Who raced TR7 V8's) when he was going to use throttle bodies using the same inlet manifolds, i think his view at the time was that they are more suited to low down tourqe ?:roll: Time will tell
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I agree that the long inlet manifolds will be a limiting factor for peak BHP because at the oscilation of the inlet charge will resonate at low RPm with the long manifolds whereas the charge will resonate at high PRM with short manifolds. (i.e, when the pulse moves back up the manifold, then returns and builds up pressure at the back of the valve just before it opens resulting in better cylinder filling.)

That was me trying to sound technical and how I understand these things.

btw, that is one smart piece of kit you got there.

ppyvabw wrote:I agree that the long inlet manifolds will be a limiting factor for peak BHP because at the oscilation of the inlet charge will resonate at low RPm with the long manifolds whereas the charge will resonate at high PRM with short manifolds. (i.e, when the pulse moves back up the manifold, then returns and builds up pressure at the back of the valve just before it opens resulting in better cylinder filling.)

That was me trying to sound technical and how I understand these things.

btw, that is one smart piece of kit you got there.

Sorry that is just plain WRONG. You need to look at harmonics. towit http://www.bgsoflex.com/auto.html and click on 'intake runner harmonic pulse prediction'

Am I being thick?

If you enter in a long manifold runner length, the calculated resonant RPM is lower!

If you enter a short manifold runner length the resonant RPM is higher.

So what I said is right.

Larger the runner, greater mass of air to oscillate meaning lower resonant frequency as the oscillations are not isochronus.

I think what Bill means is for it to be any use they need to be long for it to work at a reasonable rpm. If you input 12" which isn't an unreasonable length for say a 4 barrel even the 4th harmonic is too high to be of use to many engines. Going by that page even the pictured intake is too short.

but the theory was correct yeah?

I think the theiry is correct but in the case of the rover the optimum length inlet is very long. See if you can find a picture of the wildcat crossover itb's inlet manifold to see what i mean.

Found some pics.

http://www.triumphroverspares.com.au/html/v8.htm

About half way down.

katanaman wrote:I think what Bill means is for it to be any use they need to be long for it to work at a reasonable rpm. If you input 12" which isn't an unreasonable length for say a 4 barrel even the 4th harmonic is too high to be of use to many engines. Going by that page even the pictured intake is too short.

mmmm. I see what you mean.

ihatesissycars wrote:I think the theiry is correct but in the case of the rover the optimum length inlet is very long. See if you can find a picture of the wildcat crossover itb's inlet manifold to see what i mean.

Found some pics.

http://www.triumphroverspares.com.au/html/v8.htm

About half way down.

Those Wildcat manifolds seem shorter then the JE manifolds i am using Hopfully i should find out on Monday what figures its producing if they get it sorted if not im away for a week. so it will be a week on tuesday

So what is your real power figures??

The figures from Motoscope taken on there Dastec Rolling road are
322BHP, 282 at the wheels with torque coming in at 364, ill have to try and find time to collect the TR this week and ill post the graph on here, still half dead from a good holiday but a crap return journey home
They did mention that there should be more power to come with the inlet manifolds matched to the ports, so maybe a bit of winter porting on the manifolds
What do you reckon 322bhp--OK

What do you reckon 322bhp--OK

I'd be happy