I've wanted to do either a V6 or straight 4 swap for a while now, to put the engine fully behind the crossmember, and save a little weight. I also like the idea of having tons of room to work on it and plenty of room for a large electric fan (probably a taurus one). I've been considering both the SR20DET and KA24DE-T.. and the results I have found from them have been interesting.
I've read claims that the KA24 shares the same valvetrain / head design as the RB26DETT, although I didn't see any real source or information to back this up. However, what I have seen is dyno sheets with KA24DE-T's making the same HP or more, with tons more torque than the SR20DET. Yet.. the SR20DET is 2x the cost, there must be something I'm missing.
Any input? I'd love to see constructive discussion on both of them.
A KA is not a low compression engine. Tuning is critical in making a KA-T that doesn't eat it's self and vomit parts all over the road. Also, your pricing is not looking at what it takes to make a KA-T correctly. You need a quality turbo ($800 to $1200 starting), a manifold ($500 to $1200), injectors ($250 to $500), computer ($500 to $1600), exhaust ($200 to $800), IC setup ($250 to $900), and more random little things unless you are a good fabricator. Then with all that bolted up you will then need to pay for a dyno tune, dial in the details, and still just have the basics to run the system. If you don't care about blowing the engine up, you can push it a bit, but you will probably need a water/meth injection kit. If you want to make it as reliable as an SR, you will need another couple thousand in internals and labor to drop the compression and beef up the internals.
The reason the SR costs more is because it already comes with all the requirements of a turbo engine. If you want to DIY a turbo engine, you really need to understand that it is extremely easy to have $5000 into the engine just to get it stable... and there are still no guarantees that it won't randomly pop a weak part. An SR will run all day long with around 300HP on stock everything (assuming a T28), but will start to cost the same in upgrades as you push the envelope (after all replacing turbo, injectors, computer, etc will cost the same for the SR as a KA).
The key is what you plan to do with the car. Are you shooting for 400HP+ or just looking to double the power of the L24? If you are going for 500HP it doesn't matter which you choose because you will be basically rebuilding both engines to support that power. I would suggest looking at the website I started tossing together about things to think about when doing an SR swap, it's not complete, but it has a lot of information:
Not to argue, but the SR is no more of a bolt in swap than a KA24.
I think the biggest concern for me is budget, I see stock SR20's go for no less than 1,500 online, usually more. Then you have to add in the same components as you would any other motor. Bigger injectors, turbo, etc.
It seems to be that a KA24 with a reasonable turbo (HX35/HY35) can make 300 HP on stock components with ease.
I'd honestly perfer an SR20, just because I like their exhaust sound more. But budget constraints are in place.
The SR is a turbo engine, so it is much more "bolt on" than a KA-T. Neither bolts into the car directly, but when it comes to upgrades, the SR already has low comp pistons, oil squirters, etc. The KA was never designed to be boosted, so it is extremely tune dependent or requires rebuilding it to handle the power. To get 300HP from an SR is generally under $500, to get 300HP from a KA will be $2000+, but once you build it you will have a larger displacement turbo engine to work with.
Typically people see a KA-T running 400 HP and say "OMG LOOK AT THE TORQUE!" but then never see the engine again... and this is because it destroyed it's self the next week due to detonation or melt down. In case you haven't noticed, most people run E85 on KA-T builds that have a low budget to help offset detonation risk. It is very possible to run a turbo on any kind of engine, but if the engine wasn't designed for it, your experience becomes critical in keeping it running. If people tried to do the idiotic things they do with SRs to a KA-T you would never see them on the road.
Edited by CasperIV, 10 June 2013 - 08:49 AM.