2002 Signature ISM 500 hp

[Davidv]

I just read the thread regarding the 650 ISX wow would love extra HP but would be worried about reliability.
Has anyone upgraded the ISM to get more power, say bigger turbo, injectors exhaust modifications.
If anyone has any data on upgrading this engine and maybe a shop that could do the work I surly would appreciate the info.
Was thinking about towing a 2500 crew cab with a 8 foot camper on it, about 8000 lbs I’m sure the extra pony’s would be nice, thanks.
Dave

[vito.a]

Your ISM is already upgraded from 450 to 500hp and 1550 Ft Lbs of torque.
Remember, the ISM 500 is a 10.8L (659CI) engine and the 600/650HP ISX is 14.9L (912CI).
However, the ISM weighs only 2260# while the ISX weighs 3200#. That's a 1000# weight penalty with the larger engine. Another advantage is your 2001-2002 ISM engine should not have EGR (exhaust gas recirculation).

One of our IRV2 forum members (Tom Chelbana) had a Newmar Essex with the ISM and he installed a methanol injection system. This is not a full time system, but adds boost only when you activate it. The hard part of installing this system is finding room for the large methanol tank. You could send Tom an Instant Message and ask where he sourced the methanol system.

[tom chelbana]

We had till 6 months ago a 04 Essex with the 500 ISM with ERG system. We had the coach 14 years and drove 140K plus miles. Here is what we did to get more more and better fuel economy.
1 Changed to a K&N style air filter which we used for 130K miles
2 Built a air intake scope because Newmar opening to small
3 Put a Snow Methanol/water injection system Good for about 25 to 40 HP
4 Put on a Ugly Fix ERG controller
With these upgrades almost equals the new London Aire with X15 605
Contact me and we can share phone numbers
Newmar Man

[79cvx20]

Originally Posted by Davidv

I just read the thread regarding the 650 ISX wow would love extra HP but would be worried about reliability.
Has anyone upgraded the ISM to get more power, say bigger turbo, injectors exhaust modifications.
If anyone has any data on upgrading this engine and maybe a shop that could do the work I surly would appreciate the info.
Was thinking about towing a 2500 crew cab with a 8 foot camper on it, about 8000 lbs I’m sure the extra pony’s would be nice, thanks.
Dave

Your transmission might not be able to handle more power. Call Allison first.

[Woodman018]

My diesel mechanic friend tells me to keep my coach because of the fact that it has the ISM with the 4000 Allison which he says is a great engine and transmission but that it is actually putting out more horsepower and torque than what he would like to see for it's cubic inches. He says it should still outlast me though. I think cranking it up to more horsepower may cut into it's longevity.
Dave

[Davidv]

Thanks all for the reply’s good stuff, I had not thought about the transmission being a factor seeing it’s the Allison 4000 series and probably what the 600/650 hp units run but worth checking into also was wondering if there would be a concern in the rear end gear ratios, mine is listed on the spec sheet as 433, I wonder how many gear ratios were avalable in the signature series, kind of figuring they would all be the same. I haven’t heard of anyone dealing with this just being curious.
Take care all,
Dave

[saddlesore]

With 22.5 rubber, the 4:33's are the optimum gear ratio..


Any higher ratio would affect(reduce) the top speed gearing and fuel mileage

Any lower would affect start abilities (ability to gain speed from a stop or on a freeway merge lane)