wanting to make a 3lt turbo

[James Beaumont]

Thanks for all the info guys, my engine is burning oil so it needs to be rebuilt so there are 3 ways to go, sell, rebuild the 2.5 or make an 3lt engine which would cost more then the other 2 but more fun. Its just trying to make up my mind who could do it and which is the best way of doing it.

 

[blade7]

Take a look at the hybrid stroker builds over on Rennlist. If I was starting with a 2.5 I'd go that route.

 

[u63af]

Is that the 2.8 stroker?

i am starting to think of a 2.8 as I could then keep existing 2.5 head which has already been rebuilt, need to look into what I would need to do bottom end, think it would just be 3.0 crank, better rods and pistons with lower wrist pins. Not sure how you bed new rings onto alusil block, anyone knows if you can hone the bores? Don't fancy sending it away to get redone

 

[PSH]

Andrew Sweetenham's car was a 2.8 stroker...she was fast...422BHP and we are talking 15 years ago now...very fast on the circuit, Andrew kindly took me around Castle Coombe in it...'move over all 911's' was the theme for the session...
Don't attempt to hone the bores yourself, this is a very specialist job requiring the correct cutting stones and paste, there's probably only a handful of engineering shops able to do this in the UK. Bedding is a matter of using the correct oil and driving method, there are bedding-in oils available but using a good mineral oil will do nicely. The most important thing is how you drive the engine when new, avoid motorways where you sit for long periods at a constant speed. Without using high revs, accelerate hard and then back off letting the engine do the braking, it's important to do this a number of times on the cars first run, remembering to continue with this method every now and then on subsequent runs, this action will put load on the engine and force the rings to bed in. If you don't do this you risk glazing and thus loose a good seal. If a Turbo? avoid boost as much as possible, give the engine chance to bed in correctly.

Pete

 

[blade7]

Is that the 2.8 stroker?

i am starting to think of a 2.8 as I could then keep existing 2.5 head which has already been rebuilt, need to look into what I would need to do bottom end, think it would just be 3.0 crank, better rods and pistons with lower wrist pins. Not sure how you bed new rings onto alusil block, anyone knows if you can hone the bores? Don't fancy sending it away to get redone

All the info is on Rennlist but from memory it's a 2.5 crank with offset ground big ends to increase the stroke, Mitsubishi aftermarket rods, Chevy pistons, and thin wall iron dry liners fitted in the block. Close to 3.0 capacity, reasonably cost effective , and no need for a 3.0 crank/block/2.7 head.

 

[PSH]

Is that the 2.8 stroker?

i am starting to think of a 2.8 as I could then keep existing 2.5 head which has already been rebuilt, need to look into what I would need to do bottom end, think it would just be 3.0 crank, better rods and pistons with lower wrist pins. Not sure how you bed new rings onto alusil block, anyone knows if you can hone the bores? Don't fancy sending it away to get redone

All the info is on Rennlist but from memory it's a 2.5 crank with offset ground big ends to increase the stroke, Mitsubishi aftermarket rods, Chevy pistons, and thin wall iron dry liners fitted in the block. Close to 3.0 capacity, reasonably cost effective , and no need for a 3.0 crank/block/2.7 head.

I don't recall all of the details about Andrew's 2.8ltr but I do recall that it still had alusil bores, no liners fitted, there used to be a complete kit available from the states which I think contained, rods, crank and bearings, not seen it advertised recently, though.

Pete

 

[blade7]

Is that the 2.8 stroker?

i am starting to think of a 2.8 as I could then keep existing 2.5 head which has already been rebuilt, need to look into what I would need to do bottom end, think it would just be 3.0 crank, better rods and pistons with lower wrist pins. Not sure how you bed new rings onto alusil block, anyone knows if you can hone the bores? Don't fancy sending it away to get redone

All the info is on Rennlist but from memory it's a 2.5 crank with offset ground big ends to increase the stroke, Mitsubishi aftermarket rods, Chevy pistons, and thin wall iron dry liners fitted in the block. Close to 3.0 capacity, reasonably cost effective , and no need for a 3.0 crank/block/2.7 head.

I don't recall all of the details about Andrew's 2.8ltr but I do recall that it still had alusil bores, no liners fitted, there used to be a complete kit available from the states which I think contained, rods, crank and bearings, not seen it advertised recently, though.

Pete

I was referring to the Rennlist hybrid stroker builds when I mentioned the liners. I think the 2.8 Promax car probably had a 3.0 crank, standard length rods, and custom pistons with a raised gudgeon pin height to compensate for the extra stroke. There was a 2.8 conversion that used a 3.0 crank, standard pistons and shorter rods but apparently the rod ratio wasn't ideal.

 

[u63af]

Yeah I might look at the 2.8 as I don't want to get into putting liners etc in. If I can get away with 3.0 crank uprated rods and woosner pistons with a re-hone then this is fairly cost effective. I already have a standalone wolf ecu that I bought from States that is mapped for a 2.8.

 

[PSH]

Regarding honing, Andrew had his 2.8 honed at Serdi UK in Uxbridge West London, I also had my engine bored/honed at Serdi's on Andrew's recommendation....

cheers

Pete

 

[blade7]

That's where I'd go. How much do they charge to rework Alusil blocks ?

 

[PSH]

That's where I'd go. How much do they charge to rework Alusil blocks ?

A quick look at my receipts from 2011 give's me a receipt from Serdi UK of £1,515.60, this was for a rebore to 101mm, reface of the block, a set of IASA full race forged pistons and regrinding of the crank.

cheers

Pete

 

[blade7]

Did Serdi spec the pistons and rings for you ?

 

[PSH]

Serdi spec'd the piston's, rings are spec'd by IASA to match the pistons and engine requirements, rings are designed to hold high boost and of course include an extra ring for better sealing. I spec'd the ring gaps, details were sent to IASA for confirmation that I had got it right.

 

[u63af]

So are you running an s2 crank? Rennlist seem to discuss on offset ground crank but to me it sounds easier to just get an s2 crank.

 

[PSH]

So are you running an s2 crank? Rennlist seem to discuss on offset ground crank but to me it sounds easier to just get an s2 crank.

me?.....I'm a 2.5 man all the way...well actually it's a little bit more now, approx 2.535 ltr...

Pete

 

[blade7]

Serdi spec'd the piston's, rings are spec'd by IASA to match the pistons and engine requirements, rings are designed to hold high boost and of course include an extra ring for better sealing. I spec'd the ring gaps, details were sent to IASA for confirmation that I had got it right.

Thanks for the info Pete. I wonder if IASA have made 104.5 mm versions of your pistons or it's up to a customer to spec every dimension.

 

[blade7]

Rennlist seem to discuss on offset ground crank but to me it sounds easier to just get an s2 crank.

S2 cranks in the US are around 3 times what they sell for here. There's also a school of thought over there that the reduced big end dia works better, and there are better quality bearings available in that size. Though I've read the offset grinding and heat treatment has to be done right or it can bend the crank.

 

[PSH]

Serdi spec'd the piston's, rings are spec'd by IASA to match the pistons and engine requirements, rings are designed to hold high boost and of course include an extra ring for better sealing. I spec'd the ring gaps, details were sent to IASA for confirmation that I had got it right.

Thanks for the info Pete. I wonder if IASA have made 104.5 mm versions of your pistons or it's up to a customer to spec every dimension.

I believe that you can specify what you need, they have an online form for you to fill in your requirements, this is their website.. http://www.iasapistons.com/ingles/productos.php# I tried to open the products list but failed so can't answer whether they have the larger pistons as stock items, I found them very approachable via the phone, admittedly calls to Argentina aren't cheap..

regards

Pete

 

[u63af]

Yeah it sounded complicated with the offset grind saying the crank went "s shaped" and needs to be straightened. The price for the work you had done sounds good, suppose only extra to get a 2.8 would bet he cost of the crank.

 

[blade7]

If I used a 2.5 block I'd consider having the windage ports machined into it. Also original or aftermarket forged rods.