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400HP pump gas friendly 4.5L stroker (now with dyno numbers)
Gentlemen,
I am in the process of building a new motor for my Junk. If you feel the urge to flame me for not being "hardcore enough" let me know and I'll delete this post and go away. I may have some previously unseen shite to throw down here however, so be patient. I'll record progress, and hopefully finish with a dyno run after install.
Waiting on a red star to post pics. Not much to see yet, block dropped off for a tanking, bore and hone this morning.
---------------------------------
I have been playing with turbo charging on the 4.0L for some time (and with 4.2 and 4.0L performance as well), but always with stock compression and stroke. The gains have been great, especially with the use of certain dual pattern cams, head work, and free-flowing exhaust and intake. On ODB1 vehicles, detonation has never been an issue with proper fueling via 2 bar MAP sensors and enhanced fuel pressure with upsized injectors.
However, the sustainable limit for forced aspiration on a fairly stock engine has seemingly proved to be about 6.5 lbs giving 260-275 at the crank. Much more than that and heads start to crack on the exhaust seats. I have experienced this, and some pretty knowledgeable I6 gurus concur with me on my power ceiling.
So, how do I make more power than this in a sustainable fashion? Like they say - there is no replacement for displacement.
The goals were to run pump gas (~88/89 octane in Canada), at 8lbs of boost, and hit 400 crank ponies reliably. The secondary goal was to finally build myself a turbo specific, "4.0L rodded" stroker I6.
Based on the build plan, my primary goal should be very possible.
Here are the specs, parts ordered today:
93 block @ 0.30 overbore. ARP studs. 91 head.
1988 YJ 4.2L crank, balanced. Used for turbo specific engine due to lower rotating mass ( only 4 counterweights) - should spool faster then heavier, older 4.2 cranks or stock 4.0L crank.
As yet to be determined cam (spec'd for turbo apps).
Crane 96803 springs and 99278-12 lifters
Mopar retainers and locks, silicon bronze guides and neoprene seals.
Stock valves used, with valve seats milled out and hardened diesel engine valve seats pressed in.
(Oversize valves have proven to have negligible gains in I6 forced aspiration applications, I have been informed)
Hesco custom 8.0:1 forged chromoly stroker pistons, on Hesco shotpeened/magnafluxed and weight balanced custom machined 4.0L rods. Plasma-moly ring set.
The 8.0:1 CR will allow regular pump gas to be used, as well as gulp some serious air at 8.0lbs boost.
This engine will also run a progressive methanol injection kit, which is already installed on my Turbo YJ. However, the nozzle size and flowrate will be upsized significantly with this latest engine rendition.
Will post pics and info as project proceeds.
Gentlemen,
I am in the process of building a new motor for my Junk. If you feel the urge to flame me for not being "hardcore enough" let me know and I'll delete this post and go away. I may have some previously unseen shite to throw down here however, so be patient. I'll record progress, and hopefully finish with a dyno run after install.
Waiting on a red star to post pics. Not much to see yet, block dropped off for a tanking, bore and hone this morning.
---------------------------------
I have been playing with turbo charging on the 4.0L for some time (and with 4.2 and 4.0L performance as well), but always with stock compression and stroke. The gains have been great, especially with the use of certain dual pattern cams, head work, and free-flowing exhaust and intake. On ODB1 vehicles, detonation has never been an issue with proper fueling via 2 bar MAP sensors and enhanced fuel pressure with upsized injectors.
However, the sustainable limit for forced aspiration on a fairly stock engine has seemingly proved to be about 6.5 lbs giving 260-275 at the crank. Much more than that and heads start to crack on the exhaust seats. I have experienced this, and some pretty knowledgeable I6 gurus concur with me on my power ceiling.
So, how do I make more power than this in a sustainable fashion? Like they say - there is no replacement for displacement.
The goals were to run pump gas (~88/89 octane in Canada), at 8lbs of boost, and hit 400 crank ponies reliably. The secondary goal was to finally build myself a turbo specific, "4.0L rodded" stroker I6.
Based on the build plan, my primary goal should be very possible.
Here are the specs, parts ordered today:
93 block @ 0.30 overbore. ARP studs. 91 head.
1988 YJ 4.2L crank, balanced. Used for turbo specific engine due to lower rotating mass ( only 4 counterweights) - should spool faster then heavier, older 4.2 cranks or stock 4.0L crank.
As yet to be determined cam (spec'd for turbo apps).
Crane 96803 springs and 99278-12 lifters
Mopar retainers and locks, silicon bronze guides and neoprene seals.
Stock valves used, with valve seats milled out and hardened diesel engine valve seats pressed in.
(Oversize valves have proven to have negligible gains in I6 forced aspiration applications, I have been informed)
Hesco custom 8.0:1 forged chromoly stroker pistons, on Hesco shotpeened/magnafluxed and weight balanced custom machined 4.0L rods. Plasma-moly ring set.
The 8.0:1 CR will allow regular pump gas to be used, as well as gulp some serious air at 8.0lbs boost.
This engine will also run a progressive methanol injection kit, which is already installed on my Turbo YJ. However, the nozzle size and flowrate will be upsized significantly with this latest engine rendition.
Will post pics and info as project proceeds.