ISR Mod "capped" vs "uncapped" (performance numbers)
#1
Contributing Member
Thread Starter
Join Date: Jan 2003
Posts: 10,916
Likes: 0
Received 0 Likes
on
0 Posts
ISR Mod "capped" vs "uncapped" (performance numbers)
Some of you may recall this thread regarding the performance data on the ISR mod. In summary, I found the ISR mod to provide huge performance gains for the money, with the FPR line hooked up (uncapped).
There has been some discussion about whether or not to cap off the FPR vacuum line. Dr Z has found that by capping off the FPR line, the air/fuel ratio is richer. This provides less of a chance for pinging, and with proper tuning, better performance at high RPM at WOT. So, I decided to cap it off, and have another go at a 30-70MPH, 3rd gear, WOT test run. The test data is surprising:
1st Run: 11.92 sec
2nd Run: 12.02 sec
Capped AVG ET: 11.97
FPR line hooked up (uncapped) AVG ET: 11.66
The FPR line capped:
After a brief email discussion with Dr Z, we feel the loss in performance is caused by a rich condition at lower RPM's at WOT.
So, in my particular test, which lugs the engine at the start (2K RPM), there is a loss of performance. So, with proper tuning, or for the drag racer, the capped FPR line would work nicely. However, if you run a similar set-up as myself, where tuning is limited, then you may want to keep the line hooked up. Your call.
There has been some discussion about whether or not to cap off the FPR vacuum line. Dr Z has found that by capping off the FPR line, the air/fuel ratio is richer. This provides less of a chance for pinging, and with proper tuning, better performance at high RPM at WOT. So, I decided to cap it off, and have another go at a 30-70MPH, 3rd gear, WOT test run. The test data is surprising:
1st Run: 11.92 sec
2nd Run: 12.02 sec
Capped AVG ET: 11.97
FPR line hooked up (uncapped) AVG ET: 11.66
The FPR line capped:
After a brief email discussion with Dr Z, we feel the loss in performance is caused by a rich condition at lower RPM's at WOT.
So, in my particular test, which lugs the engine at the start (2K RPM), there is a loss of performance. So, with proper tuning, or for the drag racer, the capped FPR line would work nicely. However, if you run a similar set-up as myself, where tuning is limited, then you may want to keep the line hooked up. Your call.
#3
Contributing Member
Thread Starter
Join Date: Jan 2003
Posts: 10,916
Likes: 0
Received 0 Likes
on
0 Posts
I actually got the cap from my uncle, who had a plumbing end cap sitting around. You can go to Lowes, or any plumbing store, and find the correct end cap for your application. Just take off the IS in the parking lot, and bring it in.
I totally recommend this mod. And obviously, I recommend the FPR line hooked up.
Gaining almost .2 seconds from 30-70MPH for free (or for the cost of an end cap) is WELL worth it. Keep in mind, you should run premium fuel with this mod.
My 4Runner definetly pulls harder. Its also really loud at WOT around 4 - 5K RPM, the only drawback next to using premium fuel in my opinion.
I totally recommend this mod. And obviously, I recommend the FPR line hooked up.
Gaining almost .2 seconds from 30-70MPH for free (or for the cost of an end cap) is WELL worth it. Keep in mind, you should run premium fuel with this mod.
My 4Runner definetly pulls harder. Its also really loud at WOT around 4 - 5K RPM, the only drawback next to using premium fuel in my opinion.
#4
Registered User
Join Date: Apr 2003
Location: Indiana, PA
Posts: 234
Likes: 0
Received 0 Likes
on
0 Posts
Interesting Post!! Did you happen to notice any pinging with either the vaccuum line plugged or unplugged. I would like to do the ISR but the premium gas would put me in the poor house. :pat:
#5
Contributing Member
Thread Starter
Join Date: Jan 2003
Posts: 10,916
Likes: 0
Received 0 Likes
on
0 Posts
No, I did not notice pinging with the FPR line capped or uncapped. So, for me, premium fuel is a necessity.
On my 98 Taco, I noticed pinging while running 87 Octane. I am not taking any chances with my 96.
Here is a pic of the FPR line hooked up (my current set-up)
On my 98 Taco, I noticed pinging while running 87 Octane. I am not taking any chances with my 96.
Here is a pic of the FPR line hooked up (my current set-up)
#6
Contributing Member
Join Date: Apr 2003
Location: denver-home missoula,mt-school
Posts: 753
Likes: 0
Received 0 Likes
on
0 Posts
hey man i have been reading all about these upgrades. what exactly did you use for everything, including idameters and lenghts if you can. and where you got it. sorry for any inconvinence
#7
Registered User
Originally posted by dexter
hey man i have been reading all about these upgrades. what exactly did you use for everything, including idameters and lenghts if you can. and where you got it. sorry for any inconvinence
hey man i have been reading all about these upgrades. what exactly did you use for everything, including idameters and lenghts if you can. and where you got it. sorry for any inconvinence
https://www.yotatech.com/~corey/tech...ntake/dr_z.htm
As for getting the parts, you should be able to find them at a home center store like Lowe's or Home Depot. Personally, I got mine at Home Depot.
Have fun!
Mark
Trending Topics
#9
Contributing Member
Join Date: Feb 2003
Location: Seattle, WA
Posts: 2,858
Likes: 0
Received 0 Likes
on
0 Posts
Hey FWIW- I put the silencer containing the vacuum line nipple back on, reconnected the vacuum tube, and noticed a pretty significant increase in performance over "capped."
I still had the other two silencers removed and the deckplate out. So, guess I need to rig a vacuum nipple to a plumbing endcap now!
Just some more qualitative data to support 96's numbers.
I still had the other two silencers removed and the deckplate out. So, guess I need to rig a vacuum nipple to a plumbing endcap now!
Just some more qualitative data to support 96's numbers.
Thread
Thread Starter
Forum
Replies
Last Post
Gone Fission
General Electrical & Lighting Related Topics
4
09-04-2015 12:18 PM
FS[SouthEast]: 1992 4Runner with 3.4 5speed $2000
sphealy
Vehicles - Trailers (Complete)
1
09-03-2015 07:55 PM
Steven.m.paulk
86-95 Trucks & 4Runners (Build-Up Section)
3
07-24-2015 01:44 PM