Advice on choosing the right engine...?

The Seer · Post by **The Seer** » Sun Feb 23, 2014 7:32 pm

Soon to buy a used Dax Rush.

Looking for a car that's powered with an American engine. I'm aware that one or two appear here and there in the classifieds with Chevrolet 350 c.i's.

I have hardly any knowledge about these engines, although I'm aware there's been certain revisions since their introduction. Can anyone tell me what revision is the best to go for?

I suspect it'll probably be putting out around 250-300 bhp, going by the cars I've seen advertised over the recent years. For me I'd like the engine to knock out no less than 400-450. I don't mind spending a bit to increase the power but are certain 350's more receptive towards tuning?

Many thanks, knowledge and info greatly appreciated!

Post by **katanaman** » Mon Feb 24, 2014 12:25 am

For a dax I would be looking for an Chevy aluminium block LS engine. They are light so won't harm the handling like the old iron block chevy will and they are also compact, not a lot bigger than a rover engine. Depending what you went for you could get your power goal from a stock crate engine.

http://www.partsworldperformance.com/ for an idea of whats avaliable. There are other options on that site as well as other suppliers.

The Seer · Post by **The Seer** » Mon Feb 24, 2014 1:22 am

katanaman wrote:For a dax I would be looking for an Chevy aluminium block LS engine. They are light so won't harm the handling like the old iron block chevy will and they are also compact, not a lot bigger than a rover engine. Depending what you went for you could get your power goal from a stock crate engine.

http://www.partsworldperformance.com/ for an idea of whats avaliable. There are other options on that site as well as other suppliers.

Thanks for the link but as I said I'm not looking to buy another engine, merely looking for a car with the right engine. I'm not worried about the handling characteristics, no track days are planned.

Just want to find out what 350 is considered to be one best? I'm aware they've been in production for some time. I dare say it'll be a pre 1986 engine.

SuperV8 · Post by **SuperV8** » Mon Feb 24, 2014 12:15 pm

I think you'll need to be very very lucky to find a Rush with Chevy 350 of the exact spec your after... It wasn't a popular engine choice for the Rush I recon only a handful ever built.

Tom.

bigaldart · Post by **bigaldart** » Mon Feb 24, 2014 7:41 pm

Look for a 4 bolt bottom end, good aftermarket aluminium heads, you will probably need 200 plus runners for your goals, compression around 10-1 if its built properly and with the right cam 400 hp is doable, but you will need it to rev to get there. Have a look at the multitude of crate engines giving this kind of HP and look for a similar spec.

Alan

kiwicar · Post by **kiwicar** » Mon Feb 24, 2014 9:34 pm

Best regards
Mike

The Seer · Post by **The Seer** » Tue Feb 25, 2014 9:37 am

SuperV8 wrote:I think you'll need to be very very lucky to find a Rush with Chevy 350 of the exact spec your after... It wasn't a popular engine choice for the Rush I recon only a handful ever built.

Tom.

I'm simply after a car with a 350, not necessarily one with exactly 400 odd bhp. Just seeking the info on what's the considered one of the best revisions to look for.

Every few months or so one appears, in fact there's one on Pistonheads right now...but it has an auto transmission

The Seer · Post by **The Seer** » Tue Feb 25, 2014 9:41 am

bigaldart wrote:Look for a 4 bolt bottom end, good aftermarket aluminium heads, you will probably need 200 plus runners for your goals, compression around 10-1 if its built properly and with the right cam 400 hp is doable, but you will need it to rev to get there. Have a look at the multitude of crate engines giving this kind of HP and look for a similar spec.

Alan

This means a 4 bolt mains? What do you mean by 200 plus runners, please excuse my ignorance. Is it quite difficult to extract the power of circa 400 without uisng forced induction? (not keen on that method)

Crate engine isn't an option, if it was I might as well buy a car without an engine and there's even less of them about.

Cobratone · Post by **Cobratone** » Tue Feb 25, 2014 9:32 pm

I think the simplest answer to your question is that as the iron block chevy only put out a few BHP as per your original post and you will need to change parts to get the horsepower you want then it doesn't matter which of the gen1 iron engines you go for as it'll probably only be the block and sump you keep anyway.
HTH

kiwicar · Post by **kiwicar** » Tue Feb 25, 2014 9:50 pm

Hi
4 bolt mains are 4 bolt main caps on the middle 3 main bearings.
200 runners. . 200 cc runners in the heads.
basically 200cc to 210cc inlet runners and about 23 degrees of cam timing at .05" on a roller cam will give you a road drivable 400 to 420 BHP and a high rise duel plane inlet manifold and a well set up 4 barrel. You then just need to choose the bottom end to "shape" the power curve if you go for a 350 cu inch engine then you will probably see max power at about 6200 to 6400 revs. Put a 3.75" crank in it and it will make a bit more torque but the top end power will be about the same but at about 5800 to 6000 revs find a 400 block and build a 412 cui motor then the same top end will give you about 430 to 440 bhp at about 5600 to 5800 revs, the larger bore makes quite a big difference. Going the other way and you could go down to a 3.25" crank and it would rev well making peak power at about 6600 to 6800 revs but you may have to go to a single plane manifold, and it could be a challenge in traffic, it would still make the same numbers.
There really is no "best" 350 as you can build a 350 cui engine on a 4.185" bore out of a stock 400 block with a 3.2" stroke but finding a 400 block in the uk is not easy.
A 327 block 2 bolt main block can be converted to 4 bolt mains just by getting a set of main caps and drilling the block for the extra studs/bolts.
Avoid 350 blocks post '86 from Mexico as they tend to be porous and have thinner cylinder walls with worse core creep when cast. And an LT1 although good castings are a bit of a pain to use with earlier gen 1 stuff.
best regards
Mike

volospian · Post by **volospian** » Tue Feb 25, 2014 10:34 pm

Why do you want, specifically, an american engine, and, of those choices, specifically a 350 chevy, in a rush?

If you were after a cobra rep, I could understand it more, but a rush is more caterham 7 style. You say you want around the 400 horses figure.... that's a lot for a rush. They weigh bugger all, so 400hp would be 6-800hp per ton depending on final build weight... and a chevy 350 aint that light, so it would eat into the ratio. You may be better looking at bhp per ton figures instead of chasing a specific engine config.

mgbv8 · Post by **mgbv8** » Wed Feb 26, 2014 12:08 am

400hp in a Dax Rush would be way too much power to be of any use I think !

Whats the point of having power if you cant get it down due to the lack of weight over the rear axle and non slick tyres?

kiwicar · Post by **kiwicar** » Wed Feb 26, 2014 8:51 am

mgbv8 wrote:400hp in a Dax Rush would be way too much power to be of any use I think !

Whats the point of having power if you cant get it down due to the lack of weight over the rear axle and non slick tyres?

Hi
I was just plain ignoring that discussion. Really the best engine for a seven is a thoughtfully tuned Zetec or Duratec, alfa or vauxhall 2 litre 4 cylinder engine anything heavier un-ballances the car anything very much lighter is just too skittish.
However I will not discourage anyone wanting to own a chevy on principle and he could always build a 4 wheel drive set up to go with it to get the power down and add weight to give it traction.
best regards
Mike

mgbv8 · Post by **mgbv8** » Wed Feb 26, 2014 11:31 am

Hey!!

I'm not hating. I'm all for sticking stupid power into small cars. But thats for drag racing fun.

If I had one of these cars for road fun I would want it to handle so I would be sticking something like a Fiat 20 valve turbo lump in there. Forged pistons sport exhaust and a few other goodies will see good power. All I did with stock 20v engine was stick a 75 shot of nitrous in to make 300hp. I believe the buyer of the car now has it touching 450hp with better turbo setup.

Horses for courses I guess. If you want to use a V8 then try to get some good wide rubber on the rear end. Something like 10" wide at least I would say

unstable load · Post by **unstable load** » Wed Feb 26, 2014 11:59 am

Volvo 5 cylinder Turbo.......