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turbo with efe motor or bandit/gsxr motor?


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Just out of curiosity. what may be any benefits or drawbacks of going with either engine?

What should be done to an efe engine in preparation for ~200 or so rideable hp (td04 or vf23 or vf24. I got that part figured out...). Do they have forged pistons already good for 200 or so. Are there magic suzuki swap pistons out of another bike to use rather than 900 dollar turbo pistons. that sort of thing. 

Or is there any reasons why a person should just start with a bandit motor to do this with?

Edited by boilerdude
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All depends on how you ride / temperatures where you ride / street or strip / or both ..... boost level ..,but we all know that "just wana run lowish boost " is a short lived scenario so build  motor accordingly.turbos produce alot of heat .... and with heat ... comes all the  not so fun stuff . Which motor ?  Hmmmm.... both have thier good and bad points.... 200 hp goal is respectable but then the need for more will follow shortly ..... hp cost money !!!  The cheap route will end up costing you in the long run . Some say the cast pistons will hold..... fuck that .... the ring lands will be toast the first sign of detonation..... mtc amongst some others ,make proper forged turbo pistons for both air/oil cooled  motors...low comp and thicker crowns and ringlands...cheap alternative for oil boilers are forged slugs from gen 1 busas ....  now that is just  a small part of the equation..... fueling?? Spark control ?? 

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blow thru. maybe just get the motor prepped. Get the turbo I'd like and THEN just sortof call FBM at some point and talk about the hard stuff.

spark control? sorry i'm new to this. does the spark timing need to be varied or made variable in some radical way. Or does it just need stronger? 

Promise I'll be happy with 200. well maybe 230 would be nice. Then again I bet 250 would be just about right. But surely I would be satisfied with that...

I dont want to have to stretch the bike. I want to do 3rd and 4th gear turbo wheelies. Probably take the gearing UP 1 tooth in the front. maybe even take 1 or 2 off the rear sprocket. Old school highway bomber is what I want. Reliable for sustained runs and thousands of miles.

Edited by boilerdude
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The oiler engines are better bases for turbo abuse! A GSX will need a decent welded crank or it will twist with the high torque available at lower rpm's. Also the oil system - weak for NA is suspect for turbo use without work. Not many forged pistons as OEM fitment - Busa in a GSX will work and give a super torquey 1428 monster LOL! Deffo use forged pistons - cheaper in long run! Programmable ignition is a bonus as retard on boost stops things going bang or melting!

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Ive had a set of busa pistons for 100 bucks off Eblag for 3 years now. I know they're not the optimum shape and I know about the heat spots if you dont grind the corner thingy's off of them if your afr is bad. But they are at least forgerd vs not if I understand correctly. 

Thats funny. The seller who sold me the efe was bragging how "these motor are stronger than the gsxr motor. these are the ones with the welded crank!." fuckin bullshitter yokie. but anyway. It was still worth and a nice bike.

Whats this about torquey 1428 n/a build? Is that a thing people do? What compression does that come out to? Would it cook itself on the street ( even with bandit oil cooler or a gsxr 750 curved oil cooler and also the gs750 oil pump gears?) risk of crank walk?

nah this is leaning towards a bandit motor in the efe. Nonetheless I am curious

Edited by boilerdude
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Like already said here an oil cooled engine probably easier for 200-250hp target.

The EFE engine is really strong indeed but it has few weak spots that must be sorted out before you can squeeze out some real power.

  • Clutch back plate and springs. Torque damper springs tend to flatten over time even on stock power and turbo torque can push them through thin stock back plate. So HD back plate and springs are must for any tuned engine.
  • Crank. The crank is welded from the factory so it can withstand some power. Maybe around 200-300hp depending on use and your luck. But factory tolerances for crank throw out are a bit too loose and welds are quite light. So for serious use the crank must be disassembled, checked, assembled with tighter tolerances and welded properly. 
  • Oil system. Stock oil pressure is very low, below 0.5 bar which isn't enough for any turbo. 750 pump gears will help a little, maybe enough to keep ball bearing turbos alive. For plain bearing turbos you need construct some restriction arrangement to get required +2bars for the turbo.

Stock pistons are forged so they can handle mild boosting just fine. For higher boost proper turbo pistons are highly recommended. Helical primary gears are yet another weak spot for high power but my guess is that they are fine below 300hp on street use.

In theory if you really want just slightly over 200hp and the engine is in good condition it would be relatively easy. Just sort out the clutch, lower the compression, fit 750 pump gears and use ball bearing turbo. Should work. But then if you want to get more it means some serious work and spending (crank, pistons etc.).

Alternatively just get a low mileage Bandit engine and fit stiffer clutch spring. I'm not an oil cooled expert but I think you don't even need to drop compression for 200hp and stock cast pistons should handle that if tuned properly. When going upwards the pistons are the first thing to replace. I think the rods start to be a risk around 300hp. And probably a lock-up clutch would be a good idea somewhere around 250-300hp (same goes with the EFE engine too).

So there are pros and cons with both engines. But probably the easiest option is to get an oil cooled engine. And sell the EFE engine to me ;)

  • Like 2
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  • 1 month later...

"Clutch back plate and springs. Torque damper springs tend to flatten over time even on stock power and turbo torque can push them through thin stock back plate. So HD back plate and springs are must for any tuned engine."

So where do I find this stuff? The engine is worth taking care of no matter how twisted the rest of the bike may or may not be... Is a heavy duty backplate something I can buy somewhere or do I need to have that made? The springs I need are barnett I reckon. Should I run thick springs in all the slots? get them little wussy springs outta there?

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3 hours ago, boilerdude said:

"Clutch back plate and springs. Torque damper springs tend to flatten over time even on stock power and turbo torque can push them through thin stock back plate. So HD back plate and springs are must for any tuned engine."

So where do I find this stuff? The engine is worth taking care of no matter how twisted the rest of the bike may or may not be... Is a heavy duty backplate something I can buy somewhere or do I need to have that made? The springs I need are barnett I reckon. Should I run thick springs in all the slots? get them little wussy springs outta there?

You can get a rebuild kit from APE: http://gszone.biz/clutches.html

You can do the rebuild by yourself if you are careful and have right tools. New rivets must be welded on the back plate and the weld beads should be pretty flat. So TIG is preferred method. Also the back plate should be clamped tightly on the clutch for welding.

And just to clarify, I was talking about springs on backside of the clutch hub not clutch pack springs.

  • Like 1
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Right. I'm sure it's obvious I havent had the stuff apart yet. But sometimes it's good to know these things before I tear it apart rather than sit there clueless on what parts to even buy. Or where to get them. Rather than having to look at it all first. And then wait for the new parts while my motor is apart gathering dust. 

In short thank you for being helpful and communicative.

also got the 750 oil pump gears yesterday from that one site (drive gear was oem shelf stock and driven gear came with an oil pump obviously gutted from a bike. gear is perfectly as new looking...) 140 total

Edited by boilerdude
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  • 2 months later...

Massive balls the oil boiler might be better but I like the air cooled I did mine for not massive money cause I did the engine I had a engine that had forged pistons and a welded crank and oil gears in already so I rebuilt it my mate did all the pipe work including plenum for beers I got the turbo for nothing of another mate runs 14 psi spins back wheel and does big balled wheelies so well chuffed 

  • Like 3
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