XTM X-cellerator New engines that fit or rebuild?

[GhettoPistachio]

I've had this XTM Xcellerator for most of my life but its been sitting for like 10 years. I want to get it running but its not exactly a show piece so I'm open to options. The original xtm .18 I hear is the same as the sh .18 but even then parts are mostly discontinued so rebuilding is starting to look unachievable. Are there any engines that'll fit relatively easily in the original .18's place? The factory motor is a rear exhaust port, standard threaded shaft crank, rotary carb. Can I swap with something that has a slide carb or sg shaft? any help is appreciated.

 

[tudordewolf]

I think you've still got options.

The only challenge I see is rear exhaust / threaded crank engine. I've only ever seen side exhaust/threaded crank engines, and rear exhaust/SG Shaft engines. There are threaded crank big blocks with rear exhausts, but that's not relevant right now.

Are you positive it's threaded shaft? My hunch would be that it's SG Shaft and a GS18 (which like you say, is really an Sh.18) would be a direct fit. If you post a pic of the front of the engine showing the flywheel I'll be able to tell.

You could buy a rotary carb, redcat is selling SH ones for $15 right now, which is an absolute steal, or transplant the one you have over to a new engine. You might just need to replace some o-rings within it to freshen it up. Depending on where the servo is, changing to slide carb may not be viable, since the motion is 90 degrees offset from that of a rotary.

If it is in fact threaded crank, you might have to settle for a side-exhaust engine and find a manifold that works, something like this.

 

[GhettoPistachio]

I think you've still got options.

The only challenge I see is rear exhaust / threaded crank engine. I've only ever seen side exhaust/threaded crank engines, and rear exhaust/SG Shaft engines. There are threaded crank big blocks with rear exhausts, but that's not relevant right now.

Are you positive it's threaded shaft? My hunch would be that it's SG Shaft and a GS18 (which like you say, is really an Sh.18) would be a direct fit. If you post a pic of the front of the engine showing the flywheel I'll be able to tell.

You could buy a rotary carb, redcat is selling SH ones for $15 right now, which is an absolute steal, or transplant the one you have over to a new engine. You might just need to replace some o-rings within it to freshen it up. Depending on where the servo is, changing to slide carb may not be viable, since the motion is 90 degrees offset from that of a rotary.

If it is in fact threaded crank, you might have to settle for a side-exhaust engine and find a manifold that works, something like this.

Thank you for the response. I have the engine torn down right now so you can get the full image. The first picture is the exposed crank. The second is including a cap that screws onto the threads and holds the clutch on I believe. I'm not entirely sure if that's factory or not as the car was second-hand. It almost seems like the cap acts the same way as the bolt in the end of an SG shaft so I feel like I could make it work. I'm not opposed to tinkering to make things fit.

 

[tudordewolf]

Thank you for the response. I have the engine torn down right now so you can get the full image. The first picture is the exposed crank. The second is including a cap that screws onto the threads and holds the clutch on I believe. I'm not entirely sure if that's factory or not as the car was second-hand. It almost seems like the cap acts the same way as the bolt in the end of an SG shaft so I feel like I could make it work. I'm not opposed to tinkering to make things fit.

Well I'll be, I've never seen that particular configuration before.

You're in luck, that's more akin to a short threaded shaft than a long threaded one. The flywheel would sit up against the engine, which means SG shaft engines should fit just fine.

The issue with long threaded shaft engines is that they usually put a spacer where the flywheel would go, and the flywheel sits about 5mm away from the engine, so the whole clutch assembly is about 5mm further forward. Myself and another user just did the opposite, putting SG shaft engines into cars designed for long ones, by custom-drilling some engine mounts to scooch the engine forward.

I think the GS-18 engine would be your best bet. I haven't been able to find any other rear-exhaust small blocks except for .12 racing engines.

 

[GhettoPistachio]

Well I'll be, I've never seen that particular configuration before.

You're in luck, that's more akin to a short threaded shaft than a long threaded one. The flywheel would sit up against the engine, which means SG shaft engines should fit just fine.

The issue with long threaded shaft engines is that they usually put a spacer where the flywheel would go, and the flywheel sits about 5mm away from the engine, so the whole clutch assembly is about 5mm further forward. Myself and another user just did the opposite, putting SG shaft engines into cars designed for long ones, by custom-drilling some engine mounts to scooch the engine forward.

I think the GS-18 engine would be your best bet. I haven't been able to find any other rear-exhaust small blocks except for .12 racing engines.

I'm glad I had good reason to be stumped XD. Sounds like the GS-18 is the best bet. I'll put an order in and report back with my findings when it gets here. Hopefully this'll help someone else in the future too