Topic: On the possible 4.0 FAQ thread

[chrisfranklin]

Yesterday a 4.0L TB from a '98 Cherokee arrived by UPS -- to be installed on a 2000 2.5L TJ. With the help of a neighbor who teaches auto mechanics at the local high school (absolutely cool woman who decided to make it a day project for some of her students), I dyno-ed everything in stages. Checked the air flow, too.

Results, with stock (2.5L TB & no spacer)as baseline:

(1) Poweraid spacer only -- +2 HP, 8% less airflow (Evidently, the helix bore, lips of which extends beyond intake & TB opening, actually cuts down on airflow. But the spacer does "cool" and extend air volume, hence horsepower increase.)

(2) 4.0L TB only -- + 6 HP, 16% more airflow (no surprise here)

(3) 4.0L TB & grind out intake opening to match lower TB opening -- + 13 HP, 29% more airflow (Wow! Grinding out the intake opening did make a difference!)

(4) 4.0L TB & Poweraid helix spacer & grinded-out intake opening -- +16 HP, 2% less airflow from #3 above(overlapping helix bore is still cutting off airflow, but spacer is still cooling & increasing air volume)

(5) 4.0L TB & grind out helix bore in Poweraid spacer to match lower TB opening & grinded-out intake opening (the Big Kahuna) -- + 24 HP, 39% more airflow (Wow again; the optimal configuration, obviously)

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I use a 4.0L 62mm TB and a spacer.  Haven't ground out intake or spacer.  But, here's the thing: you are supposed to get some kind of synergistic "8hp" just by grinding out the spacer?   You figure the numerous spacer people would have already capitalized on this "gain" (and gain in sales due advertisable HP gain; hey, I buy horsepower) by just leaving out the "swirly effect."  :shock:  

I mean if there is so much Hp  available on the normally-aspirated intake-side of the 4, it makes you wonder why some company isn't offering bored out, extrusion-honed, remanufactured 4cyl intakes manifolds or just a redesigned intake manifold + porting kit +headers+fuel injectors and upgraded pump or something.  I know they have a TJ intake manifold for the 6 that flow better in the redesigned later years, that people use on older 6s.  

Sound like a good "Auction site," business case (manufacture performance 4 cyl intake manifolds for Jeep 4 cyl Wranglers; the Auction site, "TB" and "intake" guys seem to do good business).  Probably cost prohibitive for big Jeep aftermarket retailers to carry the merchandise though (then again, I did see the guy in colorado selling Jeep Window zipper partial-open kits at auction, now having them listed on Q-Tech.

[chrisfranklin]

That's it, I'm going in to the manufacturing business.  Buying a bunch of stamped aluminum alloy, get a small-volume shop in China to punch them out in TB sized squares with 62mm bore and no swirly and 4 holes for extra-long bolts.  Advertise as "tested at 11hp gain on Jeep Wrangler 4 cyl"* Cost to manufacture is, say, 5 bucks a piece, due to low-volume, not including cost of custom-fabrication tools (probably not an issue given simplicity of the boring/cutting work).

*other modifications to achieve this number not included with TB purchase

Then, sell for 50 bucks a piece at auction to maybe 1 in 200 jeep 4 banger owners (comes to maybe 3,000 or so w/ YJs/TJs 4s still on road).  We'll net fifty thousand after cost of our labor/overseas shipping/ and fees to company in US that makes such offshore manufacturing arrangements.  And we'll say it beats the going rate for spacers by $25 and it makes twice the horsepower!!  figure we have about a 6 month window before the current space manufacturers catch on and issue their own, no-swirly, Spacers.  Could be patent infringement issues (unlikely).

Course we can also do this for the 4.0 and the new TK or JK spacers.


(Am I kidding about this or not?    :cry:  :wink: )

[MA2LA]

you can generaly get a basic spacer for a little over 20 bucks on ebay. don't for get the small spacers for the cable bracket and longer bolts.

[Jeffy]

Do you have a print out?  Gaining 24hp is nice but where it is gaining it at?  I'm guessing at peak RPM which.  What about torque?  I suspect it might have dropped a bit.

We used to have a dyno print out of a that did what you did and I believe it showed a significant drop on the low-end.

[chrisfranklin]

I dunno.  I pulled that list of parts and mods adding to 24hp from a thread on 4bangerJP.  Seriously, I thought it had your name on it, Jeffy?  :|

[Jeffy]

So, you didn't dyno it then.  :?   Use the 'quote' tags if you're quoting something so we know it's not you saying it.  That would have cleared things up a bit.

As for that thread, the person never did come up with a print out.

I'd rather see no change in HP for an increase in torque.  Without a printout, you just don't know.  24hp sounds good but not if it's high up the power band.