Radical SR8
 

hi all,

new to this forum but a regular on others with the same nickname.

i've recently [as in yesterday] bought a radical sr8 lm which has had the drivetrain removed by the seller for use in one of his other projects. the entire car less engine/trans and ecu now resides in my lockup waiting for an transplant. the car has lots of tasty bits fitted [centre locks, brake upgrades, farringdon dash etc.] and was super cheap so i couldn't say no.

whilst i collected yesterday, this project has been bouncing round my head for a few months now and the original idea to fit a subaru engine has not gone away. it's compact, has a low centre of gravity, comes with a compatible[ish] transaxle, has loads of tuner/parts support and will sound awesome! helps that this is also a proven solution as precision chassis works already have their sr3 ej20 c/w porsche transaxle running in the states. as my car had an rpe in their originally i should have more space for the installation and hopefully not need too many chassis mods.

i've joined this forum as i know absolutely nothing about these engines and looking to gen up before going off to find a donor drivetrain. any tips and suggestions of threads to browse would be most welcome. currently trying to navigate through the engine models so i can choose which one i want and then go find a donor. i'm in dubai so not like i can just jump on ebay or buy a donor off here.

my initial question is this: which donor engine? as in year / model number? i think i prefer 2l [or 2.1 stroker] as it gives me greater freedom around class limits if we do take it racing and its not like i need a huge amount of torque in this thing. do i need a closed block or are the semi and open ones still good enough? i am looking to be as bombproof as possible. radical engines need a rebuild every 40hrs, i don't ever want to do anything other than service mine! intention would be to fit a forged bottom end for longevity and a solid base for future upgrades. happy with 300bhp to begin with although its also an option to go higher and have switchable maps. my current track car is a renault clio [factory cup car with sadev sequential etc] so need to learn to walk before i can run. engine install will need a full custom exhaust / intake / cooling / intercooler so plenty to think about.

transmission thoughts are to keep it subaru although i still need to investigate other options. sequential would be nice as there's not much cockpit room but £££££ so i guess i need something slick with a super short throw. 5 speed should be sufficient and i although i'd like dog gears that's also £££ so that may well wind up being an upgrade path.

so yeah, that's my intro. not a bad one for a newbie i guess! didn't take many photos as i spent most of the day rearranging space in the lock up but the ones attached at least show the engine bay space.

https://cimg0.ibsrv.net/gimg/www.sco...4e9eed5f64.jpg
https://cimg1.ibsrv.net/gimg/www.sco...27d0174e71.jpg
https://cimg2.ibsrv.net/gimg/www.sco...eda33beb1b.jpg

Nice project! You sure an ej20 will fit in there? Looks tight!

first off, have a look at Braemar auto. Australian company who make a spline and blanking plate kit to turn the subaru 5 speed into a transaxle. Fairly easy to fit, but you'l then need to split the box to put a front (now rear) LSD in it.

this kit is for the 5 speed only so your limited to the sort of power your talking about anyway. So a standard ej207 would be a good bet. That' a semi closed deck 2.0.

yeah it's tight but doable.

photos from precision chassis works' brief build thread have been lost to photobucket, but here's a vid on the dyno:


they used an sr3 as the basis [busa engine]. the sr8 was built around a 2.7 rpe v8 [2 x busa engines!] which meant a wider engine bay opening and more weight in the back, so hopefully it will be more straight forward for me. i'm also lucky in that that v8 needed lots of airflow so it has a big scoop on the top of the rear clam which i can use for intake / intercooler inlet and it has intakes in each sidepod which currently direct flow to 2 huge rads, so cooling / heat management should also be easier.

i say easi-er, not easy. going to be a test of skill this one! just the bare bones make it more straight forward as it was all designed around a heavier, much faster car.

thanks for the heads up, i've seen the various blanking kits. i was thinking 5 speed as it means an easier/cheaper day at the breakers for a donor. i don't need a cruising ratio and torque won't be a problem either so 5 are all i need. is this gearbox notably weaker?? it will be getting stripped/inspected/rebuilt anyway with LSD and new gears - at least straight cut and hopefully with dog engagement.

is the closed deck rare or not? would prefer to build from a strong base but not if going to be a pain to find. 350bhp would give me 500bhp/ton which is more than plenty but i really don't want to have to worry about engine problems for a long long time post build.

also are there any notable changes re: ECU's? I would like to use the standard ECU if possible. the radical doesn't have a display as such, just picks up basic readouts on the wheel from the data logger which is apparently compatible with just about anything. if i can keep the electrics simple then i will be happy.

All sounds good.

any idea what box is in that video? Doesn'
Look like a subaru 5 speed transaxle?????

its a boxster/cayman transaxle with adaptor plate. the guys who did this are used to stuffing subaru lumps into boxsters so i guess they went with what they know. i considered this, but couldn't see any benefit.

Makes sense ...... not cheap!

Personally, for that cash and effort id go for a sequential transaxle from someone like elite to get the ratios bang on and a proper diff!