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Sealevel Turbo M8

T

TheBreeze

Well-known member
I decided to tear my sled down this summer, and install a turbo kit. It is a 2008 M8 153. I think it will be a good learning experience, as I am relatively inexperienced when it comes to a build like this, and the only way to learn is to do it.

I have the sled torn down to a nearly bare chassis to have some bulkhead cracks fixed. I was amazed at how easy the whole tear down process has been. I will be rebuilding the top end hopefully with the help of diggerdown who was nice enough to offer his guidance, and splitting the crank to have it inspected, trued and welded. I would also like to say thank to TurboMatt for his help with the engine removal, and bulkhead fix.

Here are some pics of the progress so far.

P1010233.jpg P1010235.jpg P1010264.jpg P1010266.jpg P1010298.jpg P1010306.jpg P1010304.jpg
 
The sled has 4500 miles on it, so I am giving it a thurough inspection. It has a brand new primary clutch. I will be rebuilding the motor with a new topend, truend and welded crank, and new seals. I just took apart the diamond drive, and found a bad bearing on the output shaft, and missing teeth on the planetary gears. I am going to see if I can get the unit fixed under warranty, or else will likely replace with a DD lite. I also had the common cracks on the bulkhead others have seen, and those got welded and reinfoced.

P1010299.jpg P1010300.jpg P1010301.jpg P1010302.jpg P1010303.jpg
 
My goal is to have this sled run reliably at low boost 5-6 lbs. at 1000 ft. with minimal race fuel for most of its use, but also perform well at high altitude for about 1/3 of its miles.
 
Looking real good so far.
:rockon:
That chassis welding looks amazing.
I'm very excited about this project. Gonna be a sweat build & I hope to learn a few things along the way as well about 2 stroke turbo's.
 
Thanks guys!

I am strongly considering going with the OVS Aero 66 setup, for its simplicity and self containment, and hopefully better response for the tight tree riding we see in Michigan's Upper Peninsula. I will likely lower the stock compression, hoping to run about 6 lbs. boost on pump fuel. I am fine with having to mix in a small amount of race fuel, or octane supreme additive if slightly higher motor octane is needed with this setup at 1000ft.

I have read a lot of negative posts on here regarding the Aerochargers, but I am hoping that most of the failures people are seeing are due to simply trying to push more boost than the Aero's were designed to run.

I
 
From what I have been seeing locally, keep your stock compression if you want good throttle response. Can anyone else confirm?
 
I would be very interested as well. I am to lower compression for some added detonation protection, but if it will kill throttle response I would think twice.
 
stock comp.

I would say run stock compression and mix your fuel accordingly for your boost. M8's have a det sensor also offering a little safety. Also you are going to be running different weights which combined with the turbo will impact your bottom end a bit.
 
I would say from experience on my buddies t-900 polaris he built, he had the head taken out pretty far from compression (down to 10:1 or so) it does loose a little snap with that much out, but taking a little out of it is worth it IMO, especially at low elevation, you already are gonna have way better response just because of the whole dense air thing then we do up in the big hills. drop the compression a hair and run a garrett setup.. IMO they come on AWSOME. I had thought long and hard about running an aero, so did my buddy.. theres a reason most still run garretts, they work, and work well. the little details on them are kinda annoying(oil), but there are some new ways around that. talk to shain at twisted, I bet he will say slap a 2871 on that SOB even with that low of boost. they just feel awsome and got legs for days, as far as boondocking, if your clutched and tuned good, they come on AWSOME an its like riding a stocker when in the woods till you get into the flipper, then they just go wherever you ask. And I beleive the twisted setups run the oil injection pump to feed the turbo, then you just run premixed fuel. this works nice as then no worrying about the little electric oil pump(this is what I was worried about) I dont like worrying about crap like that. Just some thoughts for you, i just figured I would share my experiences with the whole deal and my take on turbo sizing/response. 2 strokes are interesting beasts.. big turbos run awsome on them even at low boost.
 
What I have been seeing with the local turbo boys, is that when they lower their compression, they just end up running more boost in an effort to get that feel back.

I rode a 700 Turbo Dragon with a low comp head, running about 14 lbs of boost. It was a tractor, but not fun to ride at all. No snap. When he went back up in compression it felt like a whole new sled. A sled that I might actually want to ride.

I'm biased coming off a geared down M1000 clutched for boondocking, but still! That dragon was not impressive feeling. It would climb like nobodys business, but it wasn't something I would ever consider until he raised his comp back up, and turned the boost back down to around 10-11.
 
I guess, it depends on what you want to drop for compression, how much your taking out, and the boost your running. coming of a geared down m1000 to a 700 is gonna suck, let alone one with a thined out head, also, if your main goal is just some saftey then you dont have to back the compression out that much, I dont know what stock heads are these days... but lots of guys that drop down a lot go to around 10:1 I think, only dropping to say 11 or 11.5:1 gets you the best of both worlds, a little saftey for running lower octane gas on boost, but not dropping enough bottom end its noticable. and the example of running 14# does exagerate the feel.. the bottom ends feel really weak once you wake them up with boost. if the only goal is for maybe 8# max... its a different story.

theres a million different ways to go about certain things, I just like to try to put options out for people as I know I have jumped into things that seemed good and then regreted them later.

either way, good luck on your build no matter what you end up doing.
 
I am contemplating the head decompression to hopefully run 6 lbs. on pump fuel at 1000 ft. safely. I would be fine with mixing in some octane supreme, or race at small quantites, but do not want to have to be running 1/2 race fuel. Do you think 6lbs can be achieved on a non intercooled 800 at 1000 ft. on stock compression?

I do still ride 10-12 days a winter out west, and I would like the sled to perform at high altitude as well. I am guessing at 10000 ft is where I would really be cussing the lower compression.
 
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As a flatlander and turbo expert here's the bottom line.

1. you will not run pumpgas at any boost on a 2 stroke turbo at sealevel or under 5000 feet .
2. det sensors do nothing to save a turbo 2 stroke. ( first hand experience ) cat and DOO.

3. leave the compression at 11.1 , no lower, add .035 to squish claearance.

4. There is NO susbstitute for a garrett turbo, I was one of ONLY 2 who worked and sold aero'sfrom the 1980's.. they are still just toys ,, no realiabilty or performance when compared to a garrett.

put a 2871 on it and forget it.

5. My sealevel xp800 garrett 2871 sleds use 11.5 .1 comp, .080 squish and engage at 3500rpm, INSTANT boost !!

You cannot beat a garrett with an aero for any reason..

6. coolant temps and overheating are the big concerns with low elevation turbos, coolant temps above 140 are deto inducers...keep it cold !!!

7. air to air intercoolers are useless until you are moving atleast 40 mph..
air to water are the bomb for sleds,, check out frozenboost.com.

8. there is only pain when trying to run a 2 stroke turbo on the flats on pumpgas,, I won't even talk to a person who wants me to build one,, avgas is cheap and is excellent !!!!
It is 105 motor octane , equal to vp red. cheaper and contains LOW lead content witch is still an internal combustion engines friend !!

avgas does NOT have rpm issues, the jasco test for airplave fuel dictates the octane test be done at the engines power rpm,, hence the 2800 rpm b/s we see from the race fuel companies..

many records have been set on avgas..

good luck with your sled, you'll love a turbo.they hook ya worse than crack !!

been addicted since 1983..lol

Gus Bohne
 
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Thanks for the input Gus. You say the Aero's are just toys, unreliable, etc. If you could further explain this I would greatly appreciate it. Are they just not capable of the big boost you like to run, and unreliable for you because you are overspinning the turbo, or have you seen failures even at the lower boost numbers they are designed to run?

From what I have read and researched, most that seem to dislike the aero's and question their reliability are trying to run more boost then they are designed for, and therefore causing turbo failure. Now if there are truly reliability issues with them, at boost below 10 lbs I am all ears.

I am not arguing your experiences, I would just like to better understand your recommendations. They are greatly appreciated.
 
My experiences include 5 psi up to 23 psi on the .325, 250 and .125 vein units. from 1983 thru 2003.

the turbo is sensitive on the exhaust side, the slightest amount of rust or light dust in the system distorts the veins. In fact, its refered to as the ( your fault damage excuse when you write the check for 1200 $ .)

the airflow figures are less than advertised.
even low boost requires high turbo rpm with lower than expected airflow


Just tryin to save you some grief,, don't take it as an attack on your turbo builder.. it aint.

Your workmanship is fantastic. take your time man


Gus
 
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