Cq20v RE2400

[stiglet]

... and weight at the back instead of the front, since most cars are front heavy.

[auditude]

Mike I think they are talking about independent throttle bodies, one for each cylinder. It does appeal to me but remote mounted turbos also look interesting. Long long way off for me though.

But there was a german link that fourcircle posted that had a good guide for modding the existing throttle body.

LINK

It didnt all translate in google but you get the jist to most of it.

Wow, from what I can tell from that translated page, 3B and 7A conrods are the same, and ABY are less heavy duty. I think I have heard that about ABY vs. 3B, but I didn't know that 7A conrods were the same as 3B.

[stiglet]

I think most internals are much the same as 3B on the 7A, other than the compression ratio that is.

[mikeraz1]

I think most internals are much the same as 3B on the 7A, other than the compression ratio that is.

SO if you lower the compresion on the 7A could you fit a turbo with out having to change much else?

[Error404]

for what i would cost you could probably just buy a 3B tbh Mike

[stiglet]

SO if you lower the compresion on the 7A could you fit a turbo with out having to change much else?

Not sure. I think the crank is the same, both have a stroke of 86.4. The bore on the S2 is 81, the bore on the 20v is 82.5 so the pistons must be different but i've been told just as strong. The block is near identical, as is the head. I thought the different compression ratio was acheived with different rods, but maybe it's the pistons (if thats possible )

But Alex is right, if you want to go turbo route you're better off getting a 3b engine or perhaps an entire donor car.

[DuncanM]

The pistons on the 3B are responsible for the change in CR. The 3B head is slightly different as it has water cooling passages, and different cams. Sourcing a 3B would be an obvious decision in Europe (or even an AAN), though in NA there are not many running around.

From that perspective, it makes much more sense to turbo the 7A, rather than to try to find a donor engine

[stiglet]

That's useful info, thanks

[panzerwagen]

Just for the sake of conversation...could the head be changed to a 3B?

Is the bottom half the same between the 2? If not, what could be done to reduce the cost of such a conversion. Here in the States most people will gut the engine out of Mk1 S6's or S4's or an older turbo 100 with 10v..

[stiglet]

Is the bottom half the same between the 2? If not, what could be done to reduce the cost of such a conversion. Here in the States most people will gut the engine out of Mk1 S6's or S4's or an older turbo 100 with 10v..

That's a good question! There are differences with oil returns from the turbo etc etc but don't know if the head would work.

Would be an easy way to get a bit more bore though:mischeif:

[mikeraz1]

Taken from the 034motorsport website:

Machining service for Audi 7A head to bring the water passages to 20v Turbo specification. Precision CNC machined, accurate to .0001", a direct bolt in for any Audi water manifold.

We use the 7A head for heavily turbocharged applications, mainly for the reason that the 7A heads are RARELY cracked between valve seats due to the lack of stress the heads have seen, by performing this machining procedure the head is brought to basically 3B specification.

[Acidburn]

Taken from the 034motorsport website:

that quote is true, thats what most people tend to do now as the heads are in a lot better condition, i'll be running a 7a head and i've just picked up a spare.

[mikeraz1]

that quote is true, thats what most people tend to do now as the heads are in a lot better condition, i'll be running a 7a head and i've just picked up a spare.

What work are you having done before fitting the 7a head and where are you having it done?
Cheers

[Acidburn]

ported
new bullet shape guides fitted, and machining done to take the turbo water manifold,
sodium filled exhaust valves
chambers balanced plus valves and seats cut, pressure tested and a very light skim to clean the face

[mikeraz1]

ported
new bullet shape guides fitted, and machining done to take the turbo water manifold,
sodium filled exhaust valves
chambers balanced plus valves and seats cut, pressure tested and a very light skim to clean the face

Are you going to do the work your self?