Resleeved 3.9 and forced induction

chodjinn · Post by **chodjinn** » Wed Apr 04, 2007 7:51 am

Some bad news from my part; the engine I have doesn't have top hat liners in, its just a standard 3.9 (gonna get engine number to check whether its a proper 3.9 or a resleeved 3.5).

Good news I found out where my other short block is, which has a new set of standard 3.9 liners in. The bloke who's built it said its no good for forced induction applications as a resleeved block has a high risk of dropped liners in such a case.

I can understand the thinking, but how true is this?

On a second note, anyone want a new 3.9 short block?!?

ihatesissycars · Post by **ihatesissycars** » Tue Apr 10, 2007 9:11 am

First of all i'd ask why it was resleeved as if it was due to a cracked block then fitting new standard liners won't fix that and second provided the above is fine then it should be fine to use with a turbo i would've thought?

chodjinn · Post by **chodjinn** » Tue Apr 10, 2007 9:17 am

yeah that's what I thought. I'm getting two ends of the story though, one from the numpty who built my engine, and another from the guys who resleeved the block. Still following this up . .

stevieturbo · Post by **stevieturbo** » Tue Apr 10, 2007 11:41 am

The first engine that was blown in my old car...

Was an early Rovercraft "4.0" which was a 3.5 block, re-linered to 3.9.

It was blown for a long time with no block issues.

If they are concerned about the block if using forced induction...I wouldnt even be using it n/a

chodjinn · Post by **chodjinn** » Tue Apr 10, 2007 12:34 pm

Right finally spoke to the engineering firm. This is the chronology of events according to them (whom I implicitly trust compared to the engine builder):

1. 3.5 Block brought to them and fitted with 3.9 liners (standard)
2. Returned to engine builder, put in car, blown up a few weeks later.
3. Engine builder asks for top-hat liners to be put in block, blames engineering firm for dropped liners
4. Engineering firm says they wouldn't have done the standard liners if they knew it would be for forced induction (contradicts what Stevieturbo and others have said). Refuses to reline block again until paid (still unpaid)
5. Block has remained on the shelf since (over a year)

Now, I still have to find out what block I have in my garage (fingers crossed its a late 3.9 but i doubt it). Either way, I'm probably going to get top-hat liners put in one of the blocks.

chodjinn · Post by **chodjinn** » Tue Apr 10, 2007 3:07 pm

Right the engine I have in my garage starts with 36D on the engine number. By my reckoning that means its a factory 3.9. The engine build sheet I have also states its a 'stiff block' type, so hopefully I'll be able to fit 4.6 goodies into it later on down the line (Gav to confirm pending photos!)

Post by **katanaman** » Tue Apr 10, 2007 4:49 pm

36D is just a normal block and not the enclosed mains one which means 4.6 parts argent going to fit without machining. All 3.9 blocks are stiff blocks it was only the early P5 P6 3.5 blocks that weren't.

ihatesissycars · Post by **ihatesissycars** » Tue Apr 10, 2007 4:52 pm

You can get the 4.6 bits to fit in these but not with out materila turned from the counter weights which then warrants a rebalance with lots of heavy metal put into the crank. Or so i've been told!

chodjinn · Post by **chodjinn** » Tue Apr 10, 2007 5:56 pm

Ar$e! Ah well never mind, probably just get tophat liners put in the spare 3.5 block I have and build that up as spare

ihatesissycars · Post by **ihatesissycars** » Wed Apr 11, 2007 9:50 am

ihatesissycars · Post by **ihatesissycars** » Wed Apr 11, 2007 9:54 am

Thats my other block thats going to become a 4.6. The bosses on the side that are circled lightly are where the holes for the cross bolts can go, ignore the arrow at the front.

The pics of the caps show the difference between them and the standard non crossboltable caps.

This is the 3.9 block that can house the 4.6 crank after some work, there is and slightly earlier one that has the bosses in the block but has the earlier caps. This one can't be crossbolted and if you wanted to fit the 4.6 crank you would need to turn the mains down rather than line boring the block out as the earlier caps don't have enough meat in them to take the larger journal.

chodjinn · Post by **chodjinn** » Wed Apr 11, 2007 10:15 am

yeah I definitely don't have one of those blocks, I had a good look last night.

Can't decide whether its worth me getting a late block and getting that top-hat linered rather than the 3.5.

A 4.6 short motor is no good Gav as I'd need all the peripheral crap as well.

ihatesissycars · Post by **ihatesissycars** » Wed Apr 11, 2007 10:31 am

Have you considered just staying with a 3.5 block and capacity? The 3.5 blocks are pretty much unburstable aside from the main cap fretting fault. If you were to find a good condition early block (which you probably have already) crank and rods (which again you prbably already have then get some forged pistons and arp main studs (about £800 from v8 dev's) you'll have a very very very strong bottom endcapable of supporting some proper power and no (touch wood) reliability problems.

chodjinn · Post by **chodjinn** » Wed Apr 11, 2007 10:53 am

yeah I have thought about that. There's a guy running a single turbo TR8 in Oz that's pushing 500bhp on standard internals - including pistons! I think the block/heads were O-ringed though - but that donesn't cost a fortune over here.

I know the block down south is my original 3.5 SD1 Vitesse block. Two of the liners have slipped, so its junk at the moment unless I get top-hats put it. Bonus though it already has ARP mains in it, and the crank/rods have been race balanced.

What I considered last night is holding out for some Group A rods as well - the same set has come up on ebay twice and not sold. I had also considered Forged Pistons - for the same price as sorting a late 3.9 + the 4.6 bits, plus the re-linereing, I could put the money into the pistons for the 3.5/3.9 and have a bombproof bottom end, like you said.

Certinly food for thought tho. I don't mind sacrificing capacity for the sake of some forged pistons in a tophat block. Nice!

ihatesissycars · Post by **ihatesissycars** » Wed Apr 11, 2007 11:05 am

You have a 3.5 block with a slipped liner? Blimey!

Anyways, use some standard efi rods but get them recon'd by real steal, they basically blueprint them and put arp bolts in them (they very very very strong already), recon a crank, get some forged pistons and arp studs. It really should be bomb proof but the key thing is you don't have to fork out £1000's on relinering a block and then getting some forged pistons to suit that block. Doing it this way means strength and no liner problems and less money.

All 3.9 blocks have potential to go wrong like the 4.6 blocks.