XTM 24.7 and Hyper 8 port ?????s

[vbgagnon]

I'm wondering about the shimming of these 2 engines? I'm trying to get all the power possible out of these engines without running them lean. Any ideas?

 

[Ryan with savage]

I'm wondering about the shimming of these 2 engines? I'm trying to get all the power possible out of these engines without running them lean. Any ideas?

How about a supercharger or a real Nitrous Oxide system!!!!

 

[vbgagnon]

If I wanted to spend big bucks on a system that didn't work I would just buy a v-spec or ws72.

 

[Ryan with savage]

Ouch....now thats gonna provoke a response!!!

 

[vbgagnon]

its only the truth!

 

[bigfreak]

Headshims right? In the engine builder world adjusting this changes the "deck height". A lot of guys think that removing shims from the engine increases compression and hence increases power. What it usually leads to is pre-detonation. The fuel compresses too much too quickly and explodes before the piston is in the proper position. This will destroy your engine.

If you ever have an engine modded, adjusting the deck height is something the engine builder will do. It's a lot of math and crap. I honestly don't know the formulas. You'd also have to find out the "volume" of these engines. You take the volume of the cylinder (pi*r^2 * h right?) and then you have to add in the volume of the space under the head. This is a dome shaped area and the size glow plug you use (long or short) will change this volume. You add these two together (be sure to include the height of your shims) and do some fancy math and you end up with your compression ratio. You then fiddle with the shims (add or remove) to reach your target compression ratio.

In answer to your question, I donno what shims to use. These are fairly popular engines. I think someone has probably done the math and has an idea of what would be ideal, but I donno if such a person frequents RCNT. Also, so you know the % nitro you use effect the ideal shimming. Also altitude effects it. If you live a mile above sea level, expect any combustion engine to act funny.

I think vbgagnon knows this, but for those that don't: don't play with your headshims. If you don't know what you're doing leave it stock.

 

[Ryan with savage]

its only the truth!

You really think an 8port hyper is anywhere near an WS7 or V-spec for reliablity or performance????

 

[vbgagnon]

Thats not wat I was saying, you said to get a supercharger/turbo or a nitrus system. Both have been tested and are not worth the money. I said if I wanted to spend the $$ one of those systems I would just go and buy a high dollar engine.

 

[flash]

If I wanted to spend big bucks on a system that didn't work I would just buy a v-spec or ws72.

i took it the same way ryan did. now that you got that cleared up my feelings arent hurt so bad. :smoke:

i really thought i had just seen the first negative response about a v-spec.


so what is this mill going in? and do you already have one or both?
what fuel do you plan to use?

 

[vbgagnon]

I have a hyper 7 pcr and a mbx-4 hopeing to trade it or make it into a truggy.

 

[AC48]

I didn't take it negative, I got ya vbgagnon . Those nitrous systems are a waste, just get a good engine.

 

[Ryan with savage]

Thats not wat I was saying, you said to get a supercharger/turbo or a nitrus system. Both have been tested and are not worth the money. I said if I wanted to spend the $$ one of those systems I would just go and buy a high dollar engine.

Ok bit of a mix up!

I WAS JOKING ABOUT THE "WHY DON'T YOU GET A SUPERCHARGER AND NOS ETC" I had just been reading the other threads about them being useless!!!

 

[Toycar]

If you haven't already port and polish will net some good gains.

 

[comp75]

24.7

I have to do a quick hijack. I am looking at the 24.7 for my ultra comp. How is it for tuning and power,vbgagnon?

 

[vbgagnon]

for the money you will not have a better engine. Its easy to brake in, tuning is a breeze set it and forget it. Great engine and well worth the money.

 

[comp75]

engine

Thanks for the damn quick reply. I will order it tonight. Thanks.

 

[vbgagnon]

You won't be disapointed! Just make sure you get the one with the big head, although I think the new ones come with the big head.

 

[AC48]

There are more powerful engines out there, but for the money the XTM is a great engine. Like vbgagnon said, the turning is a breeze. Its the easiest engine I've ever tuned. Also the easiest break in I've ever done. It never stalled once throughout the entire breakin.

 

[flash]

i would say stick with the xtm idea. more low-end and no tuning problems. you should be able to get by with running 30% fuel w/o messing with the head shims, but keep an eye on the piston/button to be on the safe side. after all- the 24.7 was designed for mt use.

 

[.21Rc10GT]

I was wondering if the XTM 24/7 would be a good Alum. T-maxx engine. It has great reviews, just wondering if anyone has done it with good results.