Safe power in a sumo?

[Pondrew]

Hi,

I am considering buying a sierra based Sumo with RV8. What sort of power can the Sumo chassis/ Sierra running gear take safely? I am planning to re-build/ re-bore the lump to give as much as possible.

I'm sure I read somewhere that the Sumo (not sure which model) chassis is designed for 200bhp, is this correct? I don't know what the running gear will take. Any advice?

Thanks
Andy

[shuggy69]

Hello Andy,

When the TV series "a car is born" was made they put a 350 Chevy in a Sierra based Sumo and it seamed to work very well. Must have been well over 200 BHP.

Simon

[dgosumo]

Make sure it has the MK3 strengthening of the chassis

[Pondrew]

Make sure it has the MK3 strengthening of the chassis

Let's assume it hasn't.

[Bernie]

I think there was a very good reason for putting in that extra tubing

[KevinW]

The basic sumo chassis is as good as pretty much any ladder frame chassis - its passed the SUV shake test that others would fail on.
With the tubing added, then its extra rigid: it improves the handling on an already rigid chassis.

However, the issue on power centres around the sierra/granada diff and the way it is mounted.
The Sierra/Granada donor came in a wide variety of guises, and putting >350hp through a diff designed for a 1.6 4 pot engine is asking for trouble.

A diff swap is quite easy, and you can easily upgrade to one of the diffs used for the V6 or the cosworth.

But you also need to use the latest mounting methods. Some of Den's methods from the 1990s were...well....dubious.
If in doubt, the car can be returned to have these mods added - thats what I did on my chassis, assuming its a MkIII.

Can't comment if its a MkII, and don't go there if its a Mk1.

[johnpen]

Back in 2001/3 when I built my Sumo I understood the chassis was rated for a maximum of 300 HP. Whether that rating was upped when the additional 'tubing' was added I don't know. One could guess it would allow an extra 50 HP. My Sumo just has a fairly standard 3.5 RV8 so not a problem.

[Pondrew]

Back in 2001/3 when I built my Sumo I understood the chassis was rated for a maximum of 300 HP. Whether that rating was upped when the additional 'tubing' was added I don't know. One could guess it would allow an extra 50 HP. My Sumo just has a fairly standard 3.5 RV8 so not a problem.

Cheers. That would seem OK then, as I will not get more than circa 200hp out of a 3.5 without spending so much money as to make it unviable and potentially unreliable.

[Pondrew]

How can I tell a MK1 from a 2 from a 3 by looking at a built car? I'm assuming the seller will not have built the car and may not know.

[Daryn Smith]

MK1 Chassis was designed and made to fit Ford Cortina suspension.

The latest chassis which I believe is a MKIIIb had foot well strengthening. This also included several updates to the front suspension geometry.

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