best carbs for sprint car

[hal 1]

a friend of mine is entering his car for various sprint events next year after trying it out for a few runs this year, the question is, which carbs should he fit for a 4.6 litre rover v8? he's currently got four 40s sidedraft webers, would 45s or 48s be better and if so which ones?

:confused:

[gentlefoot]

Hi mate. Where are you sprinting? I do the All Circuit at Lydden, Goodwood, Brands and Silverstoe.

My guess is you could go a bit larger but I know nothing about big engines. If you go too big you'll know because you'll lose mid range and gain top end power.

[Incorrigible]

Hi James,

what car do you run, I did a sprint at Lydden this summer (Caterham academy) I might have seen you

[gentlefoot]

I did quite a few sprints at Lydden this summer. Did the Caterham academy have its own class. If so I must have missed that one.

I'm in a Grey Golf MkII so you probably wouldn't have even noticed me

[hal 1]

Hi

I have to say that its not my car but it is a bit of a mix, its a lotus elan + 2 bodyshell on a TVR 350 chassis with the aforementioned V8, as far as i'm aware he's only been to a couple of tracks near York called Elvington there are two near each other i think, Any help would be gratefully received,
thanks

[Incorrigible]

There were 28 of us there in a field of (I think) about 140, easy to miss everyone really

It was the middle of June when we were there

[MR2Mike]

Carb size depends on the state of tune of the rest of the engine. Twin 40DCOE's would normaly be on the small side for a 2.3 litre engine, but then again the Rover isn't really a high revving engine, and if it's using the standard cams and heads then moving up to 45's may not gain very much.

[kevinday]

I'm no expert, but would downdrafts be better than sidedrafts as they are mounted in the V?

[gentlefoot]

Sounds eminently sensible. If I come across any articles on tuning that engine I'll post the link.

There must be loads of books on tuning the Rover V8. Such a popular unit.

Just checked and Demon Tweeks sell a book called "Tuning Rover V8 Engines" by David Hardcastle. It's bound to be decent. £17.99

You can't treat youself more than to buy a good (non-fiction) book I say!

[sharky55]

The old tuscan challenge cars ran quad 48 dellorto down draughts (rover v8), well modded internals though- Carrillo rods, Iceberg crank, cant remember what pistons were used might have been cosworth. Don't know if thats any use to you?

[GavinPearson]

Big is good, bigger is better, biggest is best.

Fit 48s or 50s.

[v8 racing]

Biggest is best?? you can tell your from the states!! Depends on the spec of the engine, these engines dont make very good bhp per litre figures in fact in normal stage 3/4 tune they are pretty sad!! a well put together 4.6 would only make 65 - 70 bhp per litre, 45's would easily cope with this kind of power, go too big all you end up doing is murdering the power curve.

[hal 1]

thanks for all the advice you've sent,I've passed it on and he said he's going to try downdraft 45s,thanks again.

[OverBoost]

As v8 Racing said...
45's will handle it fine, just take it for a rolling road tune so they can play around with the jetting, chokes and rampipe sizes to get the most out of it