Calling on all Apex/RX1 Engine Gurus - Convert RX1 to EFI – New Look at Old Question

[LightningPro]

Calling on all Apex/RX1 Engine Gurus - Converting RX1 Engine to EFI – New Look at old question

My plan is to convert a RX engine to EFI using parts from a Apex EFI engine components. The Apex engine has broken valves/guides & head. HAS ANYONE DONE THIS ALREADY??

I have on my shelf a RX1 engine in pieces that I am just about ready to reassemble. The cylinders have been repaired after an over boost and will get Falicon rods and low compression pistons when put back together.

I also have available a crashed Apex CHASSIS and all the available components, wire harness and all electronics just minus the engine that was used in another project.

I have available a broken Apex ENGINE. It had been worked over as far as having a ported head. It broke and spit out a bent/broken valve. Also from what I understand, the gear reduction area on the crankcase was broken from a Dyno accident but it was welded and repaired. Honestly, I have no interest in trying to fix this Apex motor because I don’t know what else has been stressed on this engine.

I own a machine shop and I used to make the Lightning Pro turbo kits for the RX sleds a while back.

Here is my project plan to convert the RX engine to EFI and boosted engine using the Apex EFI engine components and crashed apex chassis. I would appreciate help and advice on this.

1. I would make adapters to fit the Apex throttle body to fit RX intake (its ok if in different position)

2. Modify RX valve cover to accept the cam sensor (machine shop stuff)

3. Replace the generator/stator/cover and flywheel from broken Apex motor (bolt on)

4. Replace the cams and sprockets from broken Apex motor (bolt on)

5. Use the wire harness and all plug in components from crashed Apex chassis (bolt on)

6. Use Apex fuel tank assembly from crashed Apex chassis (bolt on)

I know there are probably a lot of other small details missing but I can deal with those if these major items could work.

Again, I would appreciate any help and advice on this. All comments positive and negative are welcome even if it is to say why it can't be done.

The only reason I am considering this is because I have all the parts available to me now and I don’t have to buy anything, just have to swap and reassemble.

The end result will be a low boost RX1 chassis & engine with Apex EFI, steering & seating position & a Power Commander.

Thanks in advance for the help, this has always been the best site for anything Yamaha

Bob Flores
LightningPro
231-632-6669

 

[YukonMP]

I'm no guru but this search pulled up a few relevant and possibly helpful threads.

https://www.google.com/search?client=firefox-b-d&q=efi+conversion+site:ty4stroke.com

 

[MrSled]

@Srxspec is the man.. Allen Ulmer would know about this...

 

[kinger]

You need the Apex head on the RX block and I think the rest will swap over just fine. I wouldn't try the RX head at all. Fix that ported apex head. Need all the wiring from the apex, gauge, ECU, rectifier, etc.

 

[LightningPro]

You need the Apex head on the RX block and I think the rest will swap over just fine. I wouldn't try the RX head at all. Fix that ported apex head. Need all the wiring from the apex, gauge, ECU, rectifier, etc.

Hey Thanks Kinger, I appreciate the feedback.

I was hoping to hear go ahead and use the RX engine and head. On my Haas mill, I can make adapters for the throttle bodies and make a new boss area for the cam sensor in the RX valve cover pretty easy, and for me, at less cost than replacing/repairing the valve and guide.

I would swap in the Apex cams, flywheel, stator and all electrical plug in stuff from the crashed apex chassis.

Do you think the RX head would not perform as well? Do you think there is a reason why it wouldn't work?

Also, the crank case of the apex engines has been broken and repaired before, that is why I don't want to use it, would rather sell the rest for parts.

Thanks again for your input.

 

[kinger]

If you can do that your set. I liked how you said your going to swap cams. The gear reduction that is broke in the apex is slightly different then your RX1 but I think it will be fine, also the crankshaft in the apex is lighter but I don't think that would impact tuning. No one else has a Haas and can make those adaptors and mill the valve cover so that why its always not advised. That said replacing a valve and guide should be child's play for you LOL. If that head was ported I would want to take advantage of that too. Anyway simple answer your plan will work.

 

[LightningPro]

If you can do that your set. I liked how you said your going to swap cams. The gear reduction that is broke in the apex is slightly different then your RX1 but I think it will be fine, also the crankshaft in the apex is lighter but I don't think that would impact tuning. No one else has a Haas and can make those adaptors and mill the valve cover so that why its always not advised. That said replacing a valve and guide should be child's play for you LOL. If that head was ported I would want to take advantage of that too. Anyway simple answer your plan will work.

Lol, with all the precision 3D molds and high tech work that I have done, doing a valve and guide isn't something I have done yet, maybe will still consider doing.

As far as the ported head, not sure how much performance it would add to a boosted engine, it might be worth more selling it as a ported head that needs valve/guide repair, I think it was done by OSP. I still don't know why it broke the valve in the first place, so unsure about the rest of the engine.

The case around the gear reduction shaft is what has been broken and welded. Is the gear reduction shaft and gear a different ratio on the Apex. If that is still in good shape, can that be swapped out to the RX engine. I suppose if I tear down the apex for that then the crank is available. .... the possibilities never end. Lol

At this stage, the RX engine is layed out and ready to be assembled. The Apex engine is not disassembled yet, I only want to take off what is necessary so I don't have parts spread out all over the place. Thanks again.

 

[kinger]

Yes they are different and I am not sure if they are a 'swap able' component. I always wanted to try Greg's gear reduction gears and spin the motor higher! (it literally never stops LOL )

This is from his website:

Apex/RX1 Reduction Gear Set
Pictured below is our engine PTO speed reduction gear set available for both RX1 and Apex. One of the benefits of installing a turbo is its ability to extend the power making RPM. It not only increases torque, it allows the engine to hold that torque at higher RPM’s thereby increasing HP further yet. The downside of increasing RPM is the clutch speed also increases. This increase is not favorable as far as clutch and belt efficiency is concerned. Stock RX1 engine RPM is 10200. At that engine speed the clutch speed is 8571 RPM. Now let’s increase engine RPM to 11400. The clutch speed increases to 9579. Many racers are revving the engine over 12000 RPM. This takes clutch speeds to over 10000 RPM. Belt efficiency is terrible at these elevated RPM’s. By installing one of our gear reduction sets, a RX1 engine at 12000 RPM will spin the clutch 8500. Along with the speed reduction, torque at the clutch gets multiplied as well. This allows the addition of massive amounts of weight which will give the clutch far more gripping power to hold the belt. The same holds true for Apex’s, only at a higher RPM yet. Stock Apex engines rev 10500. Apex’s have slightly more reduction than RX1’s so at that speed the clutch turns 8536. At an engine speed of 12000 the clutch will spin 9750. With our Apex drag ratio, clutch speed will be reduced to 8330.
Gear sets are available for RX1 and Apex in 2 different ratio’s, Radar run and Drag race. Gear sets are made of billet steel, heat treated and finish ground to the highest standards.