What engine is this?

[Djpohl14]

Hey guys I'm new here, I'm also new to this hobby, I recently got two used Traxxas T-maxx trucks and the guy I bought them from had bought an .25 hpi big block engine but hadn't installed it. I have looked around but had been unable to find one that looks like this? Also is it a good engine/ worth installing or should I leave in the trx2.5R that's in it?

 

[Heisenburg]

Welcome to RC Talk, DJ! These guys are pretty good at identifying old and obscure items, and should be along to help.

 

[D3MON]

that is an old HPI nitro star S 25 that came out of the savage 25, it has an aftermarket head (looks awesome on that block) i have one sitting on my bench lol, (stock head though)

sadly that wont fit your T-Maxx as your T-Maxx with the 2.5R is a small block and that HPI .25 is a big block.

personally i loved my S 25, but it needs a new sleeve/piston or needs to get pinched.

 

[D3MON]

that is an old HPI nitro star S 25 that came out of the savage 25, it has an aftermarket head (looks awesome on that block) i have one sitting on my bench lol, (stock head though)

sadly that wont fit your T-Maxx as your T-Maxx with the 2.5R is a small block and that HPI .25 is a big block.

personally i loved my S 25, but it needs a new sleeve/piston or needs to get pinched.

That HPI S25 suited my Monster GT very well when i had it in it. once one of my current engines go out, I'm planning on rebuilding it and putting it back in there.

 

[Djpohl14]

that is an old HPI nitro star S 25 that came out of the savage 25, it has an aftermarket head (looks awesome on that block) i have one sitting on my bench lol, (stock head though)

sadly that wont fit your T-Maxx as your T-Maxx with the 2.5R is a small block and that HPI .25 is a big block.

personally i loved my S 25, but it needs a new sleeve/piston or needs to get pinched.

So he also gave me a big block conversion kit traxxas part number 5360X. I'm just wondering if it is worth it, is the engine much more powerful than the 2.5R?

 

[D3MON]

yes it is very much so more powerfull, I personally would not recomend installing unless you get a 3.3 T-Maxx driveshaft set (will need hub carriers and maybe A-Arms as well, as the 2.5R ones are a bit weak and will go out quite fast, especially with big block power, you could just get extras and have them on hand, you will learn your truck really well doing that is in upside.
you may be able to prolong their lives by setting the slipper slightly loose to take the brunt of the drive force.
i am not hating on the T-Maxx as i had that exact version but even with a .18 i was blowing driveshafts on it quite often.
if you do install it you could always but the 3.3 spec driveshafts and replace when the 2.5R ones go out.
(i would definitely try to confirm what all the driveshaft conversion entails and i would suggest RPM arms/hub carriers. (id suggest RPM either way, especially the tru-Track arms for the rear.)

 

[D3MON]

yes it is very much so more powerfull, I personally would not recomend installing unless you get a 3.3 T-Maxx driveshaft set (will need hub carriers and maybe A-Arms as well, as the 2.5R ones are a bit weak and will go out quite fast, especially with big block power, you could just get extras and have them on hand, you will learn your truck really well doing that is in upside.
you may be able to prolong their lives by setting the slipper slightly loose to take the brunt of the drive force.
i am not hating on the T-Maxx as i had that exact version but even with a .18 i was blowing driveshafts on it quite often.
if you do install it you could always but the 3.3 spec driveshafts and replace when the 2.5R ones go out.
(i would definitely try to confirm what all the driveshaft conversion entails and i would suggest RPM arms/hub carriers. (id suggest RPM either way, especially the tru-Track arms for the rear.)

i say it may require those because i think the 3.3 driveshafts and arms are longer. i could be wrong, but like i said please research before you buy

 

[olds97_lss]

That conversion kit is for a revo, not a t-maxx. The issue you will have is fitting the engine in between the transmission and rear shock tower. And you also need a proper engine mount, big block manifold and pipe.

Even on the revo, only certain engines fit with that conversion kit as the starter housing hits the rear arm when it's compressed.

It's tough to find a t-maxx big block conversion these days. 15 years or so ago, there were 5-6 of them from different companies. I had the XTM conversion and a buddy of mine had the dynamite conversion. Both included a longer chassis, chassis rails, header, pipe, center/outer cvd's and engine mount. The 2.5 maxx diffs did not do well with more power though. You would likely be better off just upgrading to a 3.3 engine, then you can just drop the engine in and go. Also, it won't be so overpowered that your shelling out diffs/axles constantly.

 

[cbaker65]

As much as you have to do on a T-max ,you may as well buy another truck ,or 1/8 scale truggy!....

With that engine ,it is worth it ,if you decide to go with another ride ,make sure that it is up to date an
that parts are still available!...
That is a nice engine ,I have a brand new one that hasn't seen any fuel yet ,that is mounted on one of
my Mgt's!....