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[frog]

Picked up a 93 xr2 couple of years ago did mods to it, chip, bubble top, manual boost control set 15 psi, lowering springs, double rear sway bar, struts and brake slotted, 2" exhaust, wheels and tires. just picked up a 91 n/a body in real good shape. 93 not so good. over summer will be smushing them together and come up with a 91 xr2. I have found a lot of good info on site. I will rebuild the xr2 motor and hopefully tranny with 5th gear and lim slip. I will be doing track nite in Rockford il. a lot of miatas need their attitude adjusted. ha ha. I will update as build goes on.  If I have questions or get stuck I will reach out to ya'll. thanks for all the info.

[SHOwn]

Welcome to the team! Nice mods! Sounds like you'll test at Blackhawk Farms?

[frog]

Yes went there last year and fell in love with road racing. besides everyone at work drives scca  here so I join in fun. they drive porscha's and bimmer Just thought I would be different.   

[greywolf27030]

Sounds like a nice car.  Be sure and keep us updated.

Jack Byrd

[SHOwn]

Last time I was at Blackhawk was in the early 90's. I watched my brother race his 86 Escort GT..
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[frog]

The delimma I trying to figure out now is do I want to stay with a low compression and boost or high compression and boost. The car will most likely be a short track car 2nd, 3rd,and 4th gear mainly. short straits. I figure that the high comp. will be good for rolling out of a corner not on full boost this should help with keeping traction until the car settles out and full boost is ready and applied.. also the compression will help on down shifts into the corner. less brakes. I will keep boost at about 13 to 15 psi. any thoughts ?  . I have two running and driving cars avialble for this combo. 2 into 1 should make for a nice ride

[greywolf27030]

Your thinking parallels mine.  It would seem to me that high compression, low boost would give the best performance on the street and the type of track you're talking about.  Increasing the efficiency isn't as cheap and easy as twisting up the boost, but pays off on the bottom end and mid-range and doesn't strain the engine as much.  Besides, on the street, where do you need the power.  How much time do you spend at 6000RPM?

Jack Byrd

[Gaz]

Bump for being relevant to my interests.

[frog]

I was beer racing last nite in garage and relized something along these line. Every time I leave a stop lite and there is a car next to me I have to wait for the turbo to spool up to keep up with them after that no problem. but if I was running high compression the motor would not work as hard to make power at low/no boost. not that it takes long for ours to spool up. but that time is they are in front of me now I have to make up time. So yes !!!! it will be high compression and moderate boost for this car. besides saying 9.5 to 1 just plain sounds better than compression ratio of 7.2. Besides the girl told me that what she wants. gotta listen to her. lotta beer ha ha

[greywolf27030]

Very interested in your outcome as I've wanted to try this for years.  Back in 1963 Chevrolet built the low compression Corvair Spyder and it ran really good but a couple of years later, they put four carburetors on a high compression engine.  The N/A car could outrun the turbo to 60MPH easily.  Oldsmobile on the other hand built a high compression engine with alky injection.  That thing was a bear right off the line for 215CID.  Had both including a hopped up Corvair and always loved that Olds.  Rover used that engine for years after GM gave up on it although no turbo.

Jack Byrd

[frog]

My thinking is I may lose some volume in the cylinder for the intake charge but if you compress it into a smaller tighter package it will have a bigger explosion and more on the down stroke. and off idle to spool up should provide more power on the low end. I will be able to use this to my advantage coming out of a turn. I am also going to be using a water/meth kit. set on a pressure switch to come in at 10 psi due to the volume of air the motor will need just for cooling purpose. or I could just blow the piston right out of the motor. that would be the BIG bang theory. If this works I think I will be very happy with the set up. will the suspension handle it don't know I will tackle that one later.

[Rocketman]

The main reason the XR2 engine is such a ridiculously low compression is that they wanted the turbo engines to last - higher compression turbo setups are much more sensitive to the tune and gasoline octane/quality

I've built a high-compression turbo Capri for Russ - the result was lovely, with fantastic gas mileage to boot.

Do you need a water/meth injection setup? I have one I bought secondhand but missing the nozzle. I've never set it up, I'd be willing to sell it

[frog]

is that the car he calls suparoo or something like that. the red one.

[greywolf27030]

The main reason the XR2 engine is such a ridiculously low compression is that they wanted the turbo engines to last - higher compression turbo setups are much more sensitive to the tune and gasoline octane/quality

I've built a high-compression turbo Capri for Russ - the result was lovely, with fantastic gas mileage to boot.

Do you need a water/meth injection setup? I have one I bought secondhand but missing the nozzle. I've never set it up, I'd be willing to sell it

Great, I love the validation.  That's exactly the results I was expecting.  I expect a more advanced/tuneable  ecu would be helpful.

Jack Byrd

[greywolf27030]

will the suspension handle it don't know I will tackle that one later.

If you're more interested in handling than top down motoring, check out Festivas.  There is a guy on the Festiva Forum that had one that would outrun Corvettes.  There used to be a Corvette vs Festiva video on Youtube showing Charlie on a Phoenix road course and the Corvette couldn't keep up with him.  Charlie has a couple of Capris, but says the suspension isn't up he the power and can't be made to handle as well the Festiva.

Jack Byrd