4g61t.org

What are people getting for compression tests out of their 4g61, 4g61t? Its normal on 2.0l to see 140-160 I think right?

What is base timing supposed to be at on these too. Need to check today.

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~Jared, owner and operator of The Black Widow
10.24 @ 142.86, 1.58 60'
http://www.JayRacing.com

Factory fresh compression on a 1st-Gen 4g63 is ~165psi

The factory service "limit" on a 1st-Gen 4g63 is ~120psi

If you're in between there, you're pretty much in good shape. I think the 4g61t is rated at 8:1 compression stock, and a 4g63 is 7.8:1, so they should be pretty similar.

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

Ive got 110, 110, 115, and 120 psi. with HKS 272 cams. and n/a pistons...

do they have specs for the 4g61?

_________________
~Jared, owner and operator of The Black Widow
10.24 @ 142.86, 1.58 60'
http://www.JayRacing.com

I'm sure they do, but I don't know what the specs are. I remember back when dragstr4g61t owned that car he posted about the compression being really low like that, but the car still hauled ass so whatever. I'm not sure if the engine has been changed since then though. The N/A pistons should give it a good bump in compression though, I think they are 9:1 instead of 8:1. The cams might have an effect on the compression numbers. Also, make sure you do the test on a hot motor if you can, and hold the throttle wide-open while cranking it over, usually helps. There isn't a lot of variance between the cylinders, so that's a good thing. When in doubt, do a leakdown test!

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

NO!! I am scared to do the leakdown test.... I was scared all last season to do one... HemiColt is always making fun of me for it

I didnt think about doing it with the throttle wide open... I might do it again. Yeah bobby got 100-105psi on the old setup. Ive rebuilt this engine twice now, once due to need and once to put the na pistons in her. Ive reused the bearings and rings just like my good homie Dragstr4g61;)

_________________
~Jared, owner and operator of The Black Widow
10.24 @ 142.86, 1.58 60'
http://www.JayRacing.com

I'm sure it'll go up if you do it at WOT. Give it a shot. If the thing still runs hard, doesn't smoke too much, doesn't go through fluids, then fruit and banana it, keep running it!

_________________
91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

Tony would never lie to us.

Remember that these numbers are all skewed because of the longer duration cams, and possibly from starter speeds as well because of smaller race batteries that some people use.
Leakdown test will give a more accurate determination of sealing capability and wear characteristics.

Not intentionally!

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91 GSX - 511fwhp and 352 lb/ft 25psi 110 octane, 7.68 @ 95.9mph 1/8th 21psi 91 octane, 11.93 @ 112.9mph, 117.7mph best trap speed, 20psi 91 octane
98 Volvo S70 T5 - DD

http://www.facebook.com/captaintonus

Thanks for that! That is awesome to know for sure now;)

Yeah with my cams im sure it dropped down pretty good....

My spool and overall boost has signifigantly suffered and I am hoping my timing may have gone way out. Gonna check that later today or tomorrow.

_________________
~Jared, owner and operator of The Black Widow
10.24 @ 142.86, 1.58 60'
http://www.JayRacing.com

Got 105-120 cold on my 61t yesterday.

Also, when you went 10.9 and 10.6, was that on 61t or NA pistons?

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Current
95 Mirage AWD - "HoboEvo" 1008 awhp 9.5@165
08 535ix 420awhp
06 C6 Z06- 600whp NA

that was on the stock turbo pistons. I havent had a good pull with the na pistons. This season should have no problem

_________________
~Jared, owner and operator of The Black Widow
10.24 @ 142.86, 1.58 60'
http://www.JayRacing.com

Hot motor, WOT, cams will take some out of it, around 10ish psi.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

unfortunatly different compression testers read differently. I have had three different testers (snap on,performance tools (china) and a walmart brand one (china)... each one read differently (on the same car)... one read around 150 psi, one read 120 psi and the other around 95psi...

so u cant really measure ur compression.. and base if ur engine is good or not by compression test results... its more to check if there is indeed compression on each cylinder and that they are fairly even,

As Flying Eagle stated... a leakdown tester will give you more acurate results on the shape of your engines internal sealing surfaces

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-1989 Colt GT (stock for now)
-1993 Dodge colt 4g63 swap
-1992 Mitsubishi Lancer Evo GSR (genuine)
-1992 Eagle Summit AWD 4g63t swap (SOLD)