3.5 HO short runner. Hurt performance? - DodgeIntrepid.Net Forums - Dodge Intrepid, Concorde, 300m and Eagle Vision chat
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post #1 of 16 (permalink) Old 02-21-2007, 11:37 PM Thread Starter
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3.5 HO short runner. Hurt performance?

After looking at a couple dyno graphs, I was curious to see just how much the short runner valve helps, if any.

I unplugged the connector (threw a 2008 code btw) and did a 2nd gear run from 4000 rpm to redline. Strangely, it felt STRONGER from 5000 unwards untill the shift at 6300 rpm (police package early shift crap...).

After a couple runs I plugged the SRV back in and repeated the same thing. Sure enough, @ 5200 or so rpm, there's a noticeble dip in power. This is the valve switching over to the shorter path. From 6000 to 6300, it maybe, just maybe, pulls a bit stronger than without the SRV.

Hmm, anyone else tried this?

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post #2 of 16 (permalink) Old 02-22-2007, 12:05 AM
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That's interesting. The short runner should be better at top end. I was thinking of rigging the short runners always open for track runs, but was told that others who had tried that had poor results. I never thought about disabling the SRV and seeing what happens. I might try that in the coming months.
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post #3 of 16 (permalink) Old 02-22-2007, 12:14 AM Thread Starter
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Quote:
Originally Posted by gallotte
That's interesting. The short runner should be better at top end.
It does help the very top end, probably past 6000. But the way the police pcm is programmed, it only revs to 6300 rpm.

Right when the SRV switches, the airflow has to "fill the empty path" first, which is probably why you get a momentary dip in power on a dyno.

I figure if my engine would rev out to 6800 rpm, then eventually the shorter intake path would help. I'll get to a track when spring comes and find out which way is better.
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post #4 of 16 (permalink) Old 02-22-2007, 12:17 AM
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A prowler TCM could fix the rev limiter on my setup, but then the speedo would read wayyyyy off.
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post #5 of 16 (permalink) Old 02-22-2007, 01:58 PM
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The thing is when the short runner opens, the resonance charging ends.
It [the variable resonance valve] is closed at low speeds, and opens up to raise [double] the primary resonance frequency.
and at very high speeds, it might close again to get a second order charging effect (not here)

But by default the resonance tube is not going to be closed, [I tried it, pulled the connector-no codes, it just feels weak-large throttle/low speed 2750-4250] more than likely it only closes when the throttle is opened say 1/2 or more (it is 60 degrees in the 2gr-fe, and opens up at 4450rpm)

So without the short runners, 3.5LO '02 makes [email protected], [email protected]
3.5MO (medium output) [email protected], [email protected]
So with srv it makes [email protected], a pidly 5 hp gain.

I have pulled the little c-clip that holds the shaft to the rocker off, and lifted the pulling arm off the pin (and put the c-clip back on, don't want to lose it) so the solenoid can open the vacuum actuator ('01 here) which pulls the shaft (which is connected to the rocker which opens the SRV butterflies) so the computer doesn't go nutty. The '02 direct solenoid is faster and probably more reliable (if there isn't a vacuum source, how can the system operate?)

It sounds better, and since the programming doesn't rev beyond 6300-6400 in the 3.2, so I am not really losing anything. I am still on the original timing belt ~129K miles, so I keep the revs below 6000 now. (I upshift with autostick when the tach hits 5K-tach latency, AutoStick latency, trying to keep the SRV from opening

http://www.e90post.com/forums/showth...ighlight=stage
the rpm ranges are 0-3250, then 3250-4500, then 4500-7000 (limiter)
and everyone knows the base engine never made 215hp, 230hp. C&D said it was faster than the previous 330 (m54 with 225hp)
http://www.geocities.com/mikey9t6/car_uvwxyz_vris.htm
damn Mazda6 doesn't have this, only the jaguar versions do.

http://www.fordscorpio.co.uk/vis.htm
http://www.venommotorsports.com/libr...rickVGI268.asp
http://www.worldcarfans.com/photos.c...orsche-boxster
http://www.worldcarfans.com/photos.c...orsche-boxster

Last edited by MikeW; 02-22-2007 at 03:25 PM.
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post #6 of 16 (permalink) Old 02-22-2007, 03:57 PM Thread Starter
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Quote:
Originally Posted by MikeW
But by default the resonance tube is not going to be closed,
I'm a little confused here. Are you saying the short runner valve is ACTIVE or NON-active by default?

I know that at idle, my SRV is in the "off" position. Whether or not it opens up again at throttle positions > 0 but < 1/2 I'm not sure.

So from reading the other sites, my understanding is that the short intake path should be closed off untill 5000 rpm on our cars, right? (I'm sure we don't have the fancy 3 stage the BMW offers)

Theoretically shouldn't we see a JUMP in power at 5000 rpm if everything is designed properly? It seems that at 5000 rpm, the cylinders are not yet fighting the natural frequencies they're generating, and the SRV simply disrupts that airflow and thus requires more time before everything equalizes again.

Anyway, I just find it very difficult to feel any measureable difference in power with the SRV connected or disconnected.
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post #7 of 16 (permalink) Old 02-22-2007, 04:24 PM
 
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just leave it alone,
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post #8 of 16 (permalink) Old 02-22-2007, 05:29 PM
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No, the resonance valve is in the default open, the SRV is closed nearly all the time, how often are you 5200+rpm and 60 degrees or more throttle opening.

one would think that the long runner would be the default setting on the Neon RT magnum engine
http://faq.neons.org/2kfaq/FAQ_2KET.html#2kMAG
but the stay short at low speeds, go long for the mid range, and are back short for the 5000-6750 run.
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post #9 of 16 (permalink) Old 02-24-2007, 08:36 PM
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Smile I didn't do the mod for nothing!

I like my SRV! Ilike the extra oomph in the top end. The real goodie was the MTV which shoved the torque band down a bit and got me more torque too. The seat of the pants feel is good..... really good!
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post #10 of 16 (permalink) Old 02-24-2007, 09:01 PM
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That extra works out to like 2.5% at the tip top end, but the sound quality stinks.

I would rather have torque converter lockup in 2nd gear, 5% everywhere.
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post #11 of 16 (permalink) Old 02-25-2007, 05:05 AM
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The SRV sound is a bit weird, but it sounds mean as hell with a CAI. Torque converter lockup in 2nd would kick ass!

One thing I should note is the good old "butt dyno" is fooled by the SRV. It doesn't feel like there is more power, BUT when you look at the speedometer the truth is revealed, yup the car is a nip faster. The 70-85 jump is a bit faster, handy when you have aggressive truck drivers that think they own the road!

The 300M Special prgramming seems to have gotten me more of a boost from the tranny programming than the SRV/MTV as I ran the PCM without the active manifold for a day. When I added the manifold, I got a noticable boost but nothing like that from the firmer shifts. The shifts are a bit firm, it took me some time to get used to them, but the performance is worth it.

Oddly, the coolant temps are slightly LOWER with the new program under "having fun" conditions. Could this be due to less intentional slipping? The tranny holds third agressively, and this is helping a LOT in stop & go traffic, coolant temps are down due to less 3-4 upshifts and 4-3 downshifts.

But the most fun upgrade was the gear set..... I love torque. Being able to rev slightly in the red is kinda cool too..... 6600 RPM I think. It wasnt there long, but it didn't sound too harsh. What is the max RPM of the 3.5? I would think it would be around 6700.

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post #12 of 16 (permalink) Old 02-25-2007, 03:35 PM Thread Starter
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Max engine speed is listed as 6800 rpm. Damn, now I hate my 6300 rpm limiter even more. There's probably a less than 1000 rpm frame from the point the short runners start making power to the shift point.

Oh well, guess they didn't want heavy foot donut eaters burning through too many tax dollar funded 3.5s
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post #13 of 16 (permalink) Old 02-25-2007, 05:37 PM
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When I get the video camera from my sister, I am going to make a movie of the 6900 rev limiter on the 3.2.
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post #14 of 16 (permalink) Old 02-26-2007, 12:10 PM
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Quote:
Originally Posted by RJ
Max engine speed is listed as 6800 rpm. Damn, now I hate my 6300 rpm limiter even more. There's probably a less than 1000 rpm frame from the point the short runners start making power to the shift point.

Oh well, guess they didn't want heavy foot donut eaters burning through too many tax dollar funded 3.5s
The HP peak is around 6500-6600 RPM, so yeah, you are missing some of the fun.
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post #15 of 16 (permalink) Old 02-26-2007, 04:14 PM
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I need to find someone that can reprogram the TCM.
I need a later shift than what I am getting.
If there was a way to combine the Prowler TCM, and the 2.7 TCM, that would be the perfect programming.

As far as the SRV goes....it helps out somewhat....I will have to run some experiments at the track to see if it helps, or hurts. I can reset the code with my OBDII tool!!



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