SZ2600 Chain-Drive Turbo Engine in MM540


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Hi all

I recently modified my dads 540 and have changed the engine from di to sz2600 plus chaindrive. I have completley overhauled the engine ,i feel the power pick up and speed is not upto the mark . I need suggestions on how to increase the pickup and speed .

The config is as follows
1. 43/10 differential ratio
2. Scorpio 5+1 gb
3. 32 inch mt tyres .
4. Egr valve has been blocked .
5. Using fully synthetic oil
6. Engine overhaul done 150 kms back .

Requesting gurus to please help .
 
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Hi all

I recently modified my dads 540 and have changed the engine from di to sz2600 plus chaindrive. I have completley overhauled the engine ,i feel the power pick up and speed is not upto the mark . I need suggestions on how to increase the pickup and speed .

The config is as follows
1. 43/10 differential ratio
2. Scorpio 5+1 gb
3. 32 inch mt tyres .
4. Egr valve has been blocked .
5. Using fully synthetic oil
6. Engine overhaul done 150 kms back .

Requesting gurus to please help .

The configuration is not clear yet : A) 43\10 differential I assume is the final drive - 4.3:1. Is this the original crown/pinion ratio? This would affect
acceleration & top speed
B) 32 inch mt tyres - this would have a tyre width from 265 to 285 on a 16 " rim, which you have not clarified. This
would affect the contact patch & rolling resistance. It would help if you gave the tyre & rim size (original & modified)
in metric, eg 235/75R16
C) Any reason why the EGR valve was not re-commissioned? My Scorpio ('04 GLX) had this issue.
D) Full synthetic oil is fine - the Teflon build-up reduces liner/ring friction considerably, reducing mechanical loss.
If speed & acceleration is the only criteria then modified/competition cams, increased compression ratio etc. may be considered. Obviously, this could have
adverse effects on engine life. There are after market t /chargers with higher pressure ratios, higher mass flow rates & lower rotor inertia / turbo lag. But as with other engine mods, this too has its down-side.
Also do remember that there are no gurus here - each contributes from his/her own experience.
 
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Thread Starter #4
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The configuration is not clear yet : A) 43\10 differential I assume is the final drive - 4.3:1. Is this the original crown/pinion ratio? This would affect
acceleration & top speed
B) 32 inch mt tyres - this would have a tyre width from 265 to 285 on a 16 " rim, which you have not clarified. This
would affect the contact patch & rolling resistance. It would help if you gave the tyre & rim size (original & modified)
in metric, eg 235/75R16
C) Any reason why the EGR valve was not re-commissioned? My Scorpio ('04 GLX) had this issue.
D) Full synthetic oil is fine - the Teflon build-up reduces liner/ring friction considerably, reducing mechanical loss.
If speed & acceleration is the only criteria then modified/competition cams, increased compression ratio etc. may be considered. Obviously, this could have
adverse effects on engine life. There are after market t /chargers with higher pressure ratios, higher mass flow rates & lower rotor inertia / turbo lag. But as with other engine mods, this too has its down-side.
Also do remember that there are no gurus here - each contributes from his/her own experience.
Yes it 4.3.1
Tyres size is 32 115r 15
The egr was blocked coz it was emmitin alot of bkack smoke ,that was before the ovehaul ,and i hav heard that blocking the egr improves performance .
I am not looking at modifying any engine components ,i just need normal speed and pickup that was attained in the scorpio 2.6 turbo which i feel would be coz of the differential ratio and tyres size .

Some have suggested to go for a 44/9 config. Need inputs
 
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Yes it 4.3.1
Tyres size is 32 115r 15
The egr was blocked coz it was emmitin alot of bkack smoke ,that was before the ovehaul ,and i hav heard that blocking the egr improves performance .
I am not looking at modifying any engine components ,i just need normal speed and pickup that was attained in the scorpio 2.6 turbo which i feel would be coz of the differential ratio and tyres size .

Some have suggested to go for a 44/9 config. Need inputs
You are probably right. If the rubber contact patch and the tire outer diameter is much larger than the original, this will seriously affect acceleration. The same goes for the final drive ratios. The MM540 had a large range of final drive ratios (5.88, 4.88. 4.27) and if eg, the original ratio was 5.88 : 1 and subsequently you fitted 4.3 : 1, this would reduce torque at the wheel, thus reducing acceleration. Combining the two factors (large tire dia / width, together with an adverse final drive ratio) would definitely bring down acceleration.

No doubt large tires add to road presence, but most of the modded old Jeeps one sees on the road with monstrous tires have little to back up those looks - unless they have had serious engine mods carried out at the same time. This would certainly add muscle to those looks - but at the cost of much reduced mechanical life!
 
Thread Starter #6
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You are probably right. If the rubber contact patch and the tire outer diameter is much larger than the original, this will seriously affect acceleration. The same goes for the final drive ratios. The MM540 had a large range of final drive ratios (5.88, 4.88. 4.27) and if eg, the original ratio was 5.88 : 1 and subsequently you fitted 4.3 : 1, this would reduce torque at the wheel, thus reducing acceleration. Combining the two factors (large tire dia / width, together with an adverse final drive ratio) would definitely bring down acceleration.

No doubt large tires add to road presence, but most of the modded old Jeeps one sees on the road with monstrous tires have little to back up those looks - unless they have had serious engine mods carried out at the same time. This would certainly add muscle to those looks - but at the cost of much reduced mechanical life!
So what gear ratio are you suggesting
 
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As a ball-park figure you could try 4.88 :1, which would increase torque at the wheel, helping acceleration, without too much loss in top speed.
The following attachment gives some idea of the range of choices as far as final drive ratios is concerned. The data is from Team-Bhp (Frankenstein, dated 11th May 2011) :
 
Thread Starter #8
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As a ball-park figure you could try 4.88 :1, which would increase torque at the wheel, helping acceleration, without too much loss in top speed.
The following attachment gives some idea of the range of choices as far as final drive ratios is concerned. The data is from Team-Bhp (Frankenstein, dated 11th May 2011) :
So what would be the crown : pinion count and will it fit in d housin directly or have to change d entire differential .

No data attached
 
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My bad - here is the list of final drive ratios. The information is from Team-BHP (Frankenstein, 19th May 2011) :-

DIFFERENTIAL RATIOS / CROWN PINION.
These are the different differential ratios used for Jeeps in India.
a) 3.73:1 FOR EASY CRUISING
b) 4.27:1 CRUISING
c) 4.88:1 BALANCE BETWEEN CRUISING AND LOW END TORQUE
d) 5.38:1 MORE OF LOW END TORQUE
e) 5.89:1. MAXIMUM CRAWL RATIO FOR ROCK CRAWLING.
Note: low end torque and cruising speed may differ from engine to engine and Transmission to transmission and both together.
Sorry, cant help you regarding fitment of differential assembly / housing. I don't have the necessary knowledge.
However the following link gives some information which you can explore.:-
https://www.4x4community.co.za/foru...Difflock-on-Scorpio-Mahindra-guys-please-read
 

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