The combo is a 40 over 291 block steel crank molner rods ross pistons 2 center billet main caps. 215/220 Hyd rllr cam . Ported irons with stock rocker arms . 6766 cea turbo . 80lb injtrs with dual nozzle alky .racetronix dbl pmpr 200r4 nl ptc. Ptc frnt mount ttw 5.1 alky chip . At 27 psi my 1/8 mph was 102 & 1/4 mph was 129 . I was leaving at 0psi the track was bad I couldn't make the car hook. 2.1 & 1.9 60ft.... My stock rocker arm shaft broke on the driver side on my 3rd pass. My o2s were in the low 800s like 804 & 814 . I don't have a wide ban on the car rightnow . My 1/4 s were 11.13 / 11.26 . My exact times r posted n the timeslip n combo forum so please check them out n give me some feedback on what to do next . I'm hoping 1.6 rllr rockers help . This was on 275/60/15 Hoosier drag radials.
4.1 combo at the track
- Thread starter 007gn
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turboc87gn
Darkside in Detroit
- Joined
- Oct 2, 2008
How much boost were you running?
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27 psi boost.
m233roller
Banned
- Joined
- Jan 25, 2002
Put a pair of real slicks on the car and see what happens !!! Yup a set of 1:60 roller rockers would be great but your 60 ft. is what's killing you. Get a WIDE BAND on the car !! Good luck.
- Joined
- May 26, 2001
You posted very little info about your combo, but my guess is you have a converter issue as the general thinking of most owners in the converter is they do not want a "loose" converter, and the car will not perform well because it is too tight? 
My 4.1 street car with a TE-45A which is a 66mm turbo will slam you into the seat when floored from a stop and NOT break the M/T street radials loose, and I have done many other 4.1 GN's with a similar build and performance.
I would do 1.65:1 roller rockers to help that cam, which would not be my choice in the top 5 grinds for your application?
Get your combination correct, especially the converter, and you will have a killer street machine!
My 4.1 street car with a TE-45A which is a 66mm turbo will slam you into the seat when floored from a stop and NOT break the M/T street radials loose, and I have done many other 4.1 GN's with a similar build and performance.
I would do 1.65:1 roller rockers to help that cam, which would not be my choice in the top 5 grinds for your application?
Get your combination correct, especially the converter, and you will have a killer street machine!
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Nick, how can you recommend a change in rocker ratio based on that cam when you don't know his static compression?
Since the 4.1 is a 'tall deck' (and most people don't run .027" Cometics), I kinda want to assume it's low. Throw in extra duration and you bleed off even more cylinder pressure and VE.
Since the 4.1 is a 'tall deck' (and most people don't run .027" Cometics), I kinda want to assume it's low. Throw in extra duration and you bleed off even more cylinder pressure and VE.
Did you verify true tdc? Did you verify cam timing? How about ignition timing? Imo you should be trapping 135-136mph with those parts at 27psi. The cam isn't hurting anything and roller rockers won't add any power either. Just reliability. What is the CR?
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- Joined
- May 26, 2001
Well, I have made a recommendation similar to this a few times, and they have all worked out well.
In his case he has the 1.60 rockers, which is what I meant to post, so it is unlikely the small added lift and duration is going to throw off anything and should help when the converter change will allow faster spooling?
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