Q's about proposed KZ750 EFI turbo engine
- TexasKZ
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Re: Q's about proposed KZ750 EFI turbo engine
21 Mar 2025 15:20
I would seriously consider getting the combustion chambers and the piston crowns and skirts ceramic coated to protect them from the added heat.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24
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- Saablord
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Re: Q's about proposed KZ750 EFI turbo engine
23 Mar 2025 10:39 - 23 Mar 2025 10:51I'm working on a turbo kz750 as well and can fill in some blanks. Kawasakik1e is working on a turbo project as well.So I'm a mechanical engineering student that has made a buggy with a kz750 F LTD engine and I'm thinking about making big changes to the engine to attempt to make more power. I am planning on replacing my carburetors for fuel injection and add a turbo while I am at it. Id be aiming for a max hp of ~120. I'll be using a genuine Garrett gt1241 turbo for the conversion and I'm modifying the throttle bodies of a 2005 Yamaha r6. I have a spare engine which I plan to use the head of because of its mechanical tachometer which I should be able to use as a cam position sensor. Apologies that parts of my post may overlap with other posts I've seen on the site. here comes my list of questions so far:
Any and all input is appreciated! thanks for your help in advance.
I have realized I am essentially recreating the GPZ750 turbo engine so what are the differences between the engine internals? I know they have more aggressive cams but what else? are there any compatible parts I should look into buying?
You are definitely going to need heavy clutch springs and better clutch disks (APE is what I used). You'll want a hydraulic conversion if you do this. There are lockup clutch options as well.Does the GPZ turbo have a stronger transmission to deal with the extra torque the turbo gives? If so, how can I improve my chances of not blowing mine to pieces?
Also do the viton clutch rubbers, for sure.
I am not sure where the undercut gears, HD head studs, MLS headgasket become necessary. I'm working my way up to 150hp, so I'll find out. I'm running two kz650 254 duration intake cams with slotted gears to reduce cam overlap to about half of stock, ie about 20deg now.
Probably. There are somethings you can do to maintain the higher compression with boost. E85 fueling or water/meth. I put in a 16g aluminum gasket instead of the stock base gasket considering my end goals. stock composite head gasket still.I know the GPZ turbo has lower compression than the stock kz750, should I lower it to be on the safe side? I know in the automotive world some opt to just double up head gaskets to lower compression.
I blocked off the galley in the oil pan and installed an automotive style oil thermostat between the main galley and the rear oil pan port that allows for quick warmup but also good cooling when needed. There was a couple psi drop with this system if I remember correctly.because of extra heat from the turbo and reduced air flow because the engine is blocked by the rider I want to install a large oil cooler to help the engine stay cool. If I install a significantly large oil cooler I'm worried about how restrictive the oiling system will be with both the turbo and large oil cooler.
You should be concerned with how un-restricted the oil system will be with a turbo. stock oil pressure on the NA engines is around 8psi hot idle. most turbos want 10psi minimum. I modified my oil pump to about double the flow.oes anyone know if anyone has had problems with the oil pump being too weak? Has anyone installed a scavenging pump on their bike to combat a restrictive oiling system?
I used an external electric facet pump to handle the scavenging. I also designed an adapter plate to use a stock oil pump as a scavenge pump driven by the secondary shaft.
Ive run my EFI system on single and three phase kz650/750 generators without issue, but i am using a non-return PWM fuel pump which greatly reduces idle power consumption. LED lighting also helps.switching to an EFI system will I need to upgrade my generator?
I designed an MJF nylon 3dprinted cam sensor bung for the kz650/750 cam covers. I have a couple extras, if you'd like to buy one.mechanical tachometer which I should be able to use as a cam position sensor.
I also designed a laser cut and bent metal crank position sensor bracket that reuses the stock pickup.
Dont be scared to port the head a bit. clean up the casting line roughness, taper out the intake runners to match the TBs (as possible). Improving head flow makes turbo power easier.Are there any other performance modifications I should look into?
Figure out your control system. If you're using ITBs, youll want to use tps based tuning with map adjustment for boost. Or switch to a single TB manifold with map tuning. Map with ITBs might work with something like this efi.ttrignition.com/quadramap.html , but i havent been able to contact this vendor or try the idea.Is there anything else I should know before getting sucked too far down the rabbit hole? I'm aware there is quite a lot of work to be done fyi
Last edit: 23 Mar 2025 10:51 by Saablord.
The following user(s) said Thank You: DOHC, Gdizard
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