The V8 Owners Forum -

is it possible to take to take the crank from one of the bigger engines and put into a 3.5 without line boring/honing the mains? and if so whats the biggest engine i can take the crank from and drop into the 3.5? i have been thinking of a rover/buick 215 for my sins its a light engine BUT i want more then 250/275 horse 300-320 nm which is where the 3.5 seem to max out at in N/A form and i really dont want forced induction so im hoping for more volum and there by 300+ hp

4.2 crank at 3" stoke drops right in, the 4.6 has bigger mains and big ends. There are larger strokers available for the small journal 3.5 and some are very big, over 86 mm or 3.4"

Alan

what con rods would i need for a 4.2 swap?? i read some place that you can use ford 302 heads on the rovers is this true??

Buy Real Steel's stroker kit ?

Or Buy one of the LS based engines.

4,2 uses normal rods but pistons have shorter compression height. But, 4,2 has 94 mm bore whereas 3,5 litre has 89 mm. Or 3,7" and 3,5" if you prefer imperial units.

If you fit 4,2 crank into 3,5 litre you gain very little. Haven't done the math but around 3,8 litre. Why not go to 4,6 litre engine directly if you want more capacity and power from a Rover engine ?

And no, Ford head will not fit a Rover.

Hi
the Australian leyland p76 crank can be fitted into a 3.5 block and that gives 4.4 litres, but it would need custom pistons and custom rods. You could do it with a p76 block and the matching rods and pistons, but that would fall in half if you tried to get more than 220 bhp out of it.
However you won't get 300 bhp out of anything with rover cylinder heads, unless they are TVR bhp that is. Save your money and follow Stevie's advice and buy a chevy LS, the 4.8 of 5.3 will both deliver 300bhp with very little modification and for less money than the set of aftermarket heads for the rover that you would need to get 300bhp.
best regards
Mike

What are you trying to say Mike. Every TVR engine comes with a Dyno sheet and mine was within 10bhp of the sheet

The early 2 inch big end TVR 500 crank will slip in - has an odd rod and piston set with it and is rare. I have one. Famously quoting 340 BHP(lol)

r2d2hp wrote:What are you trying to say Mike. Every TVR engine comes with a Dyno sheet and mine was within 10bhp of the sheet

I just think it is a good job TVR no longer sell cars, the RSPCA would have much to say about the weakened state their horses always seem to be in, I think the ones in their Dynos must have been dizzy with starvation.
best regards
Mike

They were Blackpool beach donkeys.

point of using the rover engine is weight saving . seeing at they get 250-275 from a 3.5 i should atleast get 300 from a 3.8/9 the 4.2 crank i a 3.5 is i thin closer to 3.9 then 3.8 i already know about the chevy ls engine and what i can get from it i only asked for advice on the rover please dont go off track and talk about other stuff i know its advice but not the advice i needed i wont be using anything aftermarket except for intake and other small parts id end up with 4.0/2 heads because for smaller combustion chambers then the 3.5

You may have created a new standard there the
BBBDP roughly equivalent to .8bhp times distance from bar
best regards
Mike

futten wrote:point of using the rover engine is weight saving . seeing at they get 250-275 from a 3.5 i should atleast get 300 from a 3.8/9 the 4.2 crank i a 3.5 is i thin closer to 3.9 then 3.8 i already know about the chevy ls engine and what i can get from it i only asked for advice on the rover please dont go off track and talk about other stuff i know its advice but not the advice i needed i wont be using anything aftermarket except for intake and other small parts id end up with 4.0/2 heads because for smaller combustion chambers then the 3.5

I spent a lot of time and money getting 287hp from my old low comp 3500 a good few years ago. This was an old 8:1 CR engine running some nitrous on the dyno.

If you are hoping to get 300hp from a 3500 i think it may need more than a crank swap to be honest. ??

well i was thinking 3.9 liters 11:1 CR ported 4 liter heads with 29cc chambers havent decided on cam yet cause i cant find a good list of options. but i will talk to a cam company and have one custom ground if need be and some properly made headers i know about these engines performance wise what ive seen via google and youtube ive had an engine like this before but never got to the point of building it up etc this engine will not see nos or forced induction N/A only if im gonna go turbo i might aswell stay with the even fire v6 i have already

89 bore and 77 mm stroke will give 3830 cc,

No point in that combo. The real problem is the bore size. Finding suitable pistons for that particular stoke is one thing, the other is the fact that bigger bore would help the engine in breathing department. 3,9 would be a better starting point being a 94 mm bore block.

TVR 5 litre internals will physically fit in 3,9. It is also a 94 mm bore setup. Very weird combo though, long stroke, oddball short rods and allegedly modified 4,2 pistons. I have new set of said internals.

I have had both 3,5 and 4,6 engines. Ypu can get that 300 hp from a 4,6 engine with Rover heads, i got a 280+ hp with a RS Typhoon cam. And it idles at about 600-700 rpm.

Theoretocally you could get that 300 hp from a 3,5 but it will be a screamer and I doubt very much that stock internals will take it.

The weigth difference of 3,5 vs. 4,6 short engine is maybe 15-20 kg ? Not really an isue in a road car, I would choose that 4,6 engine any day over a 3,5.