Most Suitable Circuit Race 4 Cylinder Turbo Engine

[260DET]

Say around 400whp capable with a rear drive gearbox that will handle such power, a Mustang Ecoboost would do but virtually unavailable in Straya so back to square one. Spending too much money on the other project so this would be a 'done properly but not lavishly' thing for circuit racing so no crate engine, used Japanese preferred but not essential. Thinking that someone here may just have experience with a not so popular engine that goes better than it looks.

[Neverdone]

Do you just not want to go with the obvious choice of the SR20, or are you asking if there's a better, cheaper, turbo 4 out there?

 

The only other option I could even think of that "could" be done on the cheap-esk side of things would be a Mitsubishi 4G63, or possibly a Volvo B234 or a BMW M42. 

 

All the engines have issues and different sets of costs associated with them, and I don't know if you could get them up to the 400 mark cheaper then the SR.

[rturbo 930]

Well, if we're gonna throw motors that come non-turbo into the ring, I'd suggest a Honda K series. And if we're talking about something capable of 400hp, I don't think an M42 is a contender.

[Neverdone]

There are 400hp+ M42s, but it's probably more work then is worth it.

 

And good point about the K series. I've seen people adapt them to BMW ZF 5 speeds out of the E36/46. 

 

It still all comes back around to if any of these are going to  be anywhere near as expensive as a similar SR setup though.

[Chickenman]

Audi 1.8T or 2.0T. Longitudinal engine out of an Audi A4 or Passat. Rod change and 400 WHP easy peasy.  Tons of HP parts available available.  Engine strong as a rock, other than Rods. ( Bend over 300 ft.lbs torque ). Lots of good forged rods available. Integrated Engineering make excellent rods. Stock pistons are good up to the 500 BHP range. 

 

Transmission. The longitudinal transmission handle up to 800 HP drag Racing. They are AWD so you would have to lock out the front drive stubs. But that should not be too hard. They do it in British Touring Cars with the Audi's. Transform them into RWD. 

[ZROSSA]

k series honda would be my pick if  we were doing it with out any bias. However you should also look at the  2.5 l's and /or 2.7  from toyota, nissan , mazda as well. All alloy blocks and can be mated to a lot of different transmissions. Remember the mazda is sold as a ford in the US and they have done a lot of real race development on that engine. I have also been playing with the VW vr engines. Same size as a 4 cylinder, little heavier, up to 3.6 lt and 300 hp N/a. I also have a 2.3 5 cylinder version. Might put that in my AW11 one day 

 

Cheers,

 

Douglas

[260DET]

Thanks fellas for the very useful contributions, cheers. I should have mentioned that using an auto trans is a option but weight is crucial with this project, at present I'm looking at what autos may bolt up to a SR20DET, the manual option for it would be the Silvia gearbox with a close ratio Kameari gear set which is the sensible option. But 'sensible' does not always win LOL

[Gollum]

While the K is enticing, it's not cheap to build for RWD application. Going F20/2C would save a good chunk of change, and the only benefit of substance the K has over the F is displacement, which again means you're adding costs to the K argument because you're talking about building a Frankenstein engine with a K20 head with a K24 bottom. The S2000 transmission is just fine, and the stock internals will do 400whp well within any stress margins (I've seen much higher than that on factory internals). But due to the relatively high compression ratio, you won't be running cheap pump gas at those power levels. But that's the same as any motor.

 

The F motor would likely cost a bit more to build than a SR, but it should make for a vastly superior race motor since it'll make considerably more power per psi of boost. Would be an ideal use case for the new garrett G660 in my opinion. Spools like a T28, but has enough flow to shame any T3/T4 you've ever seen. Would easily keep up with the F motor up to 400whp, and likely be making minimum boost bellow 3k in any gear.

[260DET]

6 hours ago, Gollum said:

While the K is enticing, it's not cheap to build for RWD application. Going F20/2C would save a good chunk of change, and the only benefit of substance the K has over the F is displacement, which again means you're adding costs to the K argument because you're talking about building a Frankenstein engine with a K20 head with a K24 bottom. The S2000 transmission is just fine, and the stock internals will do 400whp well within any stress margins (I've seen much higher than that on factory internals). But due to the relatively high compression ratio, you won't be running cheap pump gas at those power levels. But that's the same as any motor.

 

The F motor would likely cost a bit more to build than a SR, but it should make for a vastly superior race motor since it'll make considerably more power per psi of boost. Would be an ideal use case for the new garrett G660 in my opinion. Spools like a T28, but has enough flow to shame any T3/T4 you've ever seen. Would easily keep up with the F motor up to 400whp, and likely be making minimum boost bellow 3k in any gear.

 

So, a Honda 2000 engine and gearbox? I like the sound of that, BUT, will the gearbox handle turbo power? I know that you said that the transmission is fine but how fine? I'm thinking that 400 horses at the wheels would be tops.

 

A budget engine rebuild would be lower compression pistons and stock everything else? Wonder how it would go with E85 fuel with the stock pistons?

[Gollum]

Those transmissions have done wheel stands in stock form. It'll be fine.

[Gollum]

But really, there are countless of people pushing 400+ on factory motors. Many of them indeed put on a 2mm headgasket to lower the compression, and run them like that just fine. Those types of builds I regularly see people street driving 450+whp on 91 octane pump gas (no water/meth, truly just pump fuel). There ARE people running factory compression on pump gas over 400whp. I'd imagine they're probably a bit knock limited in lower RPMs, so your tuning has to be perfect, but that's life with a high tolerance motor.

 

But my guess is that a completely factory unopened motor running E85 could push 600whp forever as long as the tune was good.

[260DET]

Thanks Gollum, I had a feeling that you would come up with something interesting and practical.

[turbogrill]

The Mazda/Ford 2.5 is becoming a popular swap into 2006-2016 Miatas, they are light and dirt cheap and most turbo builds are about 300whp - 400whp on junkyard engines. Not sure where the limit is.

 

The engine bolts up to a NC Miata transmission so no RWD conversion issues. You can also use the miata oilpan if needed. There are aftermarket turbo manifolds both RWD and FWD applications. The Mazdaspeed engines also uses this engine and same manifold. But has a crappy k04 turbo. But it does have stronger internals.

 

 

Cheapest engines seems to be from Ford Escape. Maybe a mazdaspeed3 bolts up to the transmission, in that case that might be easiest for your power levels since they are forged.

 

https://dynotronicstuning.3dcartstores.com/DYNOTRONICS1-GOAL-MK2-TURBO-SYSTEM_p_1322.html

 

Edited February 19, 2021 by turbogrill

[260DET]

My dreams exceed my capacity so this idea has been put to bed. But there is a turbo version of the Mazda 2.5 which obviously has a lot of potential, if I was proceeding that would be a favourite.

[260DET]

The project has been revived 😊 There is lots of good advice above but the used engine market in Oz is a lot different to that in the US, basically more expensive with limited availability. So I decided on a Toyota 2.7 2TR-FE with matching 5 speed Toyota auto, both low mileage which is important. There is an aftermarket controller available for the auto which was a crucial factor. Motor will be stripped for forged pistons and con rods, not sure about which turbo at present, ECU will be a Haltech Elite 1500 which will run the VVT. Might start a build thread some time.