supercharging an engine with big valve heads

[slideways]

Hi All
i'm seriously thinking of getting a supercharger but i have a modified top end, i.e stage3 big valved heads 72 mm plenum,45mm radius trumpets and inlarged inlet manifold, full decatted exhaust,
The question i have is will i see gains over a stock engine when adding a blower or do these mods become redundant
Thanks in advance

Rich

[VerySideways]

Big valve heads means it's easier to get gas in and out of the combustion chamber. A supercharger is designed to force more gas into the combustion chamber so you've made it easier to do that so you should be able to make more power...

[GreenV8S]

The better the engine's inherent breathing, the better a supercharger conversion will work.

[slideways]

thanks fellas, thats what i was hoping to hear supercharger it is then.
i'll call it a belated xmas pressy
Rich

[450Nick]

I'm running a charger along with 45mm carbon trumpets, 72mm throttle, and a full decat and it seems to run pretty well to me! I thought about doing the heads but SC-Power advised me that it wouldn't make much difference when charging, though it must do some good??

What decat exhaust do you have? I had the ACT exhaust which will not fit with the charger bracket in place so I worked with Tim at ACT to create a new manifold for the nearside to fit with the rest of his exhaust. He will do this as an exchange item for a good price if you require it.

Edit: One more thing, what cam are you running? Anything hotter than an MC-1 won't work as the cam requirements are very different. In answer to your question, I don't think the big plenum, trumpets etc make much difference on a FI engine. In fact SC-Power found gains on their 500 engine by putting a 400 trumpet base on so in some cases, smaller diameters can be better due to increased gas velocity. Well worth charging though, the power is addictive!

Edited by 450Nick on Sunday 28th December 01:12

[slideways]

450Nick said:

I'm running a charger along with 45mm carbon trumpets, 72mm throttle, and a full decat and it seems to run pretty well to me! I thought about doing the heads but SC-Power advised me that it wouldn't make much difference when charging, though it must do some good??

What decat exhaust do you have? I had the ACT exhaust which will not fit with the charger bracket in place so I worked with Tim at ACT to create a new manifold for the nearside to fit with the rest of his exhaust. He will do this as an exchange item for a good price if you require it.

Edit: One more thing, what cam are you running? Anything hotter than an MC-1 won't work as the cam requirements are very different. In answer to your question, I don't think the big plenum, trumpets etc make much difference on a FI engine. In fact SC-Power found gains on their 500 engine by putting a 400 trumpet base on so in some cases, smaller diameters can be better due to increased gas velocity. Well worth charging though, the power is addictive!

Edited by 450Nick on Sunday 28th December 01:12

Hi Nick
i'm running an MC-1 cam and a SS standard style exhaust , i spoke to colin a sc power he did say that he didnt think the n/a mods would make a difference, but he couldn,t be 100% sure as to what results i would get as he said he hadn,t done one yet, thats why i asked on here as there are some knowledgable people that have got blowers and other mods. so have you had yours on the rr yet whats it making now
Rich

Edited by slideways on Sunday 28th December 01:53

[450Nick]

Ah right you should be fine then I would think. Mine made 390 on Austec's rollers, but Paul reckoned that his RR was reading 30bhp below RR's used to test the other chargers so it's "around 400". Numbers aside though, Colin reckoned that it was on par with Dave's 500 which is 420 IIRC and certainly feels quick enough after out-dragging Cerb's and Tuscan S' at Brands a few weeks ago.

Its hard to say whether or not my induction mods made any difference as I am running a larger charger, injectors, ACT exhaust and an Emerald ECU as well so all of these things probably have an effect, but it did make a fair bit more than the 450 demonstrator so I'm sure they contributed.

Edit: I'm not that far from you I don't think as I'm just off Junction 6 M25 across the bridge so if you want to have a look at the install/have a go or have a chat about the DIY install etc to talk yourself into it then drop me a PM whenever...

Edited by 450Nick on Sunday 28th December 03:25

[slideways]

450Nick said:

Ah right you should be fine then I would think. Mine made 390 on Austec's rollers, but Paul reckoned that his RR was reading 30bhp below RR's used to test the other chargers so it's "around 400". Numbers aside though, Colin reckoned that it was on par with Dave's 500 which is 420 IIRC and certainly feels quick enough after out-dragging Cerb's and Tuscan S' at Brands a few weeks ago.

Its hard to say whether or not my induction mods made any difference as I am running a larger charger, injectors, ACT exhaust and an Emerald ECU as well so all of these things probably have an effect, but it did make a fair bit more than the 450 demonstrator so I'm sure they contributed.

Edit: I'm not that far from you I don't think as I'm just off Junction 6 M25 across the bridge so if you want to have a look at the install/have a go or have a chat about the DIY install etc to talk yourself into it then drop me a PM whenever...

Edited by 450Nick on Sunday 28th December 03:25

Thanks Nick i may take you up on that offer,

[450Nick]

Well when I said anytime, I should have said not between the 3rd and 9th Jan as I'm away, then not after the 12th as I have to head back up to Birmingham... Sorry to be a pain but you're still welcome around the dates I'm here!

[GreenV8S]

The cam requirements are going to depend on what sort of blower you're using. If you're using a centrefugal blower which mainly comes in at the top end then blow-through is unlikely to be a problem so you could use a conventional cam. If you're using a big positive displacement blower then at low rpm there could be a big problem with blow through and a shorter cam could work better (and stop you incinerating the exhaust).

[450Nick]

Thanks Peter, I think SC Power advised using a long duration cam. Not looked into the details of why yet though. Colin tells me they're working with a company to produce a cam to go with the charger systems at the moment, I'd like to see how it differs to standard road cams as I don't know much about them at present.