Stroking a 3.5

chodjinn · Post by **chodjinn** » Tue Jul 29, 2008 2:40 pm

Looking at options to increase the displacement of a 3.5 block without changing the liners. I'm info'd up on larger capacity blocks etc as Gav was looking into it a yr or so ago, but not too sure about the small bore block.

So, stroker cranks? What if I fitted a TVR 5 litre crank, would that give me 4.4litres?

And how available are the old 4.2/4.8 cranks?

Only thinking about increasing displacement as the turbo I've just got has a rather large exhaust housing and it'll need all the help i can give it to get it spooling

cheers

kiwicar · Post by **kiwicar** » Tue Jul 29, 2008 3:30 pm

Hi
From memory there are buick/holden leyland australia cranks that give 4.4 litres with a 3.5 bore, there is also a stroker crank set up sold (I think still sold) by Real steel that gives 4.3 litres with a 3.5 bore. 4.6 litre crank will need the mains turning down but again should be possable to do (not sure about oil pump for this) 4.2 crank I don't know enough about. beyond that I have seen crank blanks for sale around the place (I think boosted had some a while ago) that you can machine to about 96 mm throw.
If you want to get exotic then there are various NASCAR chevy rods with small big end sizes that with some suitable pistons or little end bushes would let you off set grind the standard crank a bit.
Mike

Wotland · Post by **Wotland** » Tue Jul 29, 2008 4:03 pm

Real Steel sold in the past an 4.3 stroker for 3.5 block :

There is also the buick 300 crank alternative :

I think V8Tuner has one 86mm stroke crank for small journal block.

Wotland · Post by **Wotland** » Tue Jul 29, 2008 4:08 pm

For the crank :
http://www.v8tuner.co.uk/product.php?id=407

Different possible combo between Rods/Pistons/Heads:
http://www.aluminumv8.com/tech/tech.htm

chodjinn · Post by **chodjinn** » Tue Jul 29, 2008 6:52 pm

Hmm, well I already have the rods and hopefully pistons soon and can't afford to change them. The buick 300 crank and P76 would have to be machined along with a few other bits.

If I got the mains turned down on a 4.6 with, say 3.5 rods and pistons what capacity would that be?

Same question with the TVR 5 litre crank, which should bolt straight in as is, but give less than 5litres? Think a new crank is out of my budget really

Wotland · Post by **Wotland** » Tue Jul 29, 2008 7:19 pm

In theory :
4.6 crank (82mm stroke) with 3.5 bore : 4072cc
TVR 5.0 crank (90mm stroke) with 3.5 bore : 4469cc

chodjinn · Post by **chodjinn** » Tue Jul 29, 2008 7:30 pm

That's more like it, cheers! Hmm, question is, would the 5litre crank take abuse given its penchant for breakage, maybe if it were nitrided/tuftrided? Could get it cross drilled as well, and radius'd oil holes . . .

Post by **katanaman** » Tue Jul 29, 2008 7:46 pm

not sure about this at all but I seem to remember the tvr crank didnt use standard sized journals. I seem to remember demo saying something about that when he was building his motor.

Wotland · Post by **Wotland** » Tue Jul 29, 2008 8:04 pm

Pretty sure TVR 500 crank have 2.3'' small main journals as they didn't use X-Bolted block.

chodjinn · Post by **chodjinn** » Tue Jul 29, 2008 8:10 pm

It would be handy if they were 2.3" as I already have a set of 77 bearings spare

Post by **katanaman** » Tue Jul 29, 2008 8:14 pm

no they didnt use cross bolt block but they did use the intermediate block with the closed mains. The size wasn't small or large journal anyway it was unique to TVR as the cranks were. Could be completely wrong here but it is in the back of my mind they were different for some reason.

TVRleigh · Post by **TVRleigh** » Wed Jul 30, 2008 10:38 am

chodjinn wrote:Hmm, well I already have the rods and hopefully pistons soon and can't afford to change them. The buick 300 crank and P76 would have to be machined along with a few other bits.

If I got the mains turned down on a 4.6 with, say 3.5 rods and pistons what capacity would that be?

Same question with the TVR 5 litre crank, which should bolt straight in as is, but give less than 5litres? Think a new crank is out of my budget really

You would be better off selling the TVR 5ltr crank, than re-grinding it.
The money you would save on the re-grind and the sale of the TVR crank, you could by the stuff you need and may even have change.

chodjinn · Post by **chodjinn** » Wed Jul 30, 2008 11:13 am

I dont have a 5 litre crank?! I haven't got any at the moment, apart from two standard 3.5s . . .

TVRleigh · Post by **TVRleigh** » Wed Jul 30, 2008 2:44 pm

chodjinn wrote:I dont have a 5 litre crank?! I haven't got any at the moment, apart from two standard 3.5s . . .

Ok, I would not even think about trying to get one,

You could get a Complete S/H 3.9 Engine for the price of a 5ltr crank.

chodjinn · Post by **chodjinn** » Wed Jul 30, 2008 4:23 pm

true, but i dont want a second hand 3.9 bag of poop because it wouldn't last five seconds. TVR cranks have gone for little in the past; even DJE is selling one at under £500 right now, but I wont deal with him period.

Its looking increasingly like I'll stick with a 3.5 crank, maybe a group A spec one or equivalent (been offered a Group A crank for £350 but I think that is a bit too much!), and make a revvy little basta'd and sling in some nitrous to help spool the turbo up. For the price of a stroker crank, I could get a nice nitrous system . . . oh dear evil thoughts lol.

Water/methanol injection is also on the shopping list.

As is either a bigger intercooler, or swapping it out for a chargecooler. All a long way away, but food for thought none the less.