I may have the opportunity to do this for quite cheap, as a local gentleman requires the 4.1 gear to run a stock car engine within the regulations.

I'd like to get all your thoughts regarding this... whether you think it could be a straightforward swap, if the 4.1 cams would work fine with the longer stroke, etc.

Try talking to Mirage as I think he's done it.

They have the same 220.35mm deck height, so that suggests it could work.

Yeah Ezekial and I discussed the deck height, but that won't indicate whether the main journals are the same diameter, etc. I've send Mirage an e-mail, hopefully he replies in due course

I would presume there is some reason the VH45DE has the lower crank girdle and is so much more robust on the lower end.

The VH41DE has a 6 bolt, crossbolted, one piece mains girdle. You're presuming the VH41DE to be different on the bottom end than the 45, but I'm pretty sure they're the same.

Local Daves stockcar (4litre (250ci?) approx restriction, 10:1 and carby) which Cambridge Engine Services built uses the 45 with the 41 crank etc. I'm pretty sure they said only the piston gudgeon height was the only difference.I have seen the heads which run the (huge) std valve size yet with modded ports/cams and a 4 barrel runs extremely well at over 500hp. They kept the 45 heads (1 port per valve) and ported them to try to obtain midrange torque. I think when it was dynoed with std cams and the other present mods it put out 440hp from memory. They estimate over 500hp, and dave said that it went heaps better once the cams were done. I must say I video'd it last time I was at his place and play it now and again...sounds great! If anyone wants this vid leave email, or tell me where I can host it.

I just rang the gentleman from cambridge engine services and asked him all about it, he thinks it's a great idea and that the internals would swap straight over... although he did say that the pistons are a different compression height so I'll definitely need to take that into account.

ultrapulse wrote:I must say I video'd it last time I was at his place and play it now and again...sounds great! If anyone wants this vid leave email, or tell me where I can host it.

Here in the multimedia forum.

siamese heads ftw!

youtube or streetfire will host the video for you, also

I nearly got a 41 and fitted the 45 crank myself. After all they are basically the same engine. BTW my simplex chain on my last vh didnt break when the cam ceased into the head, but did shear the cam dowel and break the plastic chain runner on that side. However have replaced that one, and doing the other side for approx NZ$80 which i thought was ok for a non-nz engine. The heads dont flow that much differently, but for a drag racer or any peak hp engine the guys here say the 41 would be the go. Both heads were within about 5-8hp and approx 495-498hp, but cant remember at what lift. Jim has the flow data sheets. Plus my 45 port job is a little more exotic. I also want midrange.I will try to upload that video. Only thing is 3 meg is heaps for dialup

on your 45 port job, did you just bore the intake ports out with an end mill? I looked on my heads, and it looks like you can only squeeze out each port to about 1.2" before you break through to the other port.

Here is the stockcar small vid to get an idea:zerothread/190987

Also defrag I didnt 'bore them out' as the problem there is that you would stuff up the small side radius down by the ports valve bowl. You dont really want to take much if any metal away from this radius. I mainly took it away at the port top, trying to slightly more downdraught the port, as well as a general blend of the already large bowl area to the smaller port, and did this all the way down. Too me for ever. As well as where the 2 ports meet they blend together with quite a sharp divider. I cant really explain, and a piccy tells 1000 typed words! Will get a couple of pics. Also I saw what the guys that built the stockcar did and was quite a good idea, just different. Ended up with two D-shaped ports back to back at the manifold end..enabling an oval manifold to be easily made. I dont really want to explain too much as its not for me to tell. But yes Jim the main man might be a grumpy **** sometimes, but he will be the one in charge of cam specs and assembly of mine.While on this note, I want to use Farrea super alloy valves, yet there is no listing. Has anyone here used them? If so please give part numbers. I will be getting in contact with them when the time comes.http://www.ferrea.com/productlines.php

Nice, that motor sounds tough as. How much different is my fuel injected street motor going to sound with some nice extractors & free flowing intake ?