NICEHATCH

I


Modified by NICEHATCH at 5:48 PM 7/20/2008

Speedra500

back pressure does not help power, did you dyno on the same dyno, use the same wheels, or change any drivetrain components?

The Phil

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NICEHATCH &raquo;</TD></TR><TR><TD CLASS="quote">To my dismay I was shocked that the car actually lost power throughout the power-band as Engine Builder had indicated to me over the phone. He claimed that I lost about 6 whp and 6 wtq. Which really is quite frustrating to fathom. However in this game it's mix and match and see what works.

From the looks of things, Engine builder is speculating that with the new muffler which was installed is causing a drop in much needed back pressure. Due to the fact that I only have stock cams! Initially the blah blah blah</TD></TR></TABLE>

Bahahahaha. *points and laughs*

h22aBB4

do a search, i think in the faqs there is a section about backpressure. despite popular belief, back pressure will not help horsepower. jw- why do you say your car can get at least 209 horsepower? why not a nice and round number like 210?

dc2vu

You made more power by going richer? I was under the assumption that your tune should be around 13.3-13.5 optimally.

NICEHATCH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Speedra500 &raquo;</TD></TR><TR><TD CLASS="quote">back pressure does not help power, did you dyno on the same dyno, use the same wheels, or change any drivetrain components?</TD></TR></TABLE>

Yeah I happened to go from a 6-puck sprung paddle clutch to a 4-puck unsprung. So back-pressure doesn't help? Can it be the actual diameter size change on the actual exhaust inlet on the muffler? I went from a 2.25 to a 2.5...I was told that you want to have the exhaust actually streamlined which makes the car produce more power?

I'm just baffled as to what the issue is. I spoke to the tuner not to long ago and he indicated that with the baseline run with the new bolt on's it did <U>190 whp</U>. Then with tuning, finagling, and playing with cam gears he was able to get 196 whp.

I figured I would make + more whp with the bolt-ons however something is not equating.

Thanks for the feedback.

NICEHATCH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dc2vu &raquo;</TD></TR><TR><TD CLASS="quote">You made more power by going richer? I was under the assumption that your tune should be around 13.3-13.5 optimally.</TD></TR></TABLE>

Yeah...however even with a baseline run from the new set-up it made 190whp without tuning or playing with the a/f ratio. So I definately lost power. I am not sure why?

Tuner indicates weather conditions. I'm not exactly sure if that is the case. I can't explain why the exhaust change would yeaild lower whp?

BlueLude84

That is pretty weird...
If anything, shouldnt it give you more whp?

98vtec

let me get this straight, you went from 201whp to 196whp?

NICEHATCH

Here is the muffler in which I used...

The actual muffler I switched to was the Dynomax Ultra-Flow Welded Performance muffler.

Here's the link:http://www.dynomax.com/products/ufw.asp


Brand: Dynomax Performance Exhaust
Product Line: Dynomax Race Mufflers
Case Shape: Oval
Inlet Diameter (in): 2.500 in.
Inlet Quantity: Single
Inlet Location: Offset
Outlet Diameter (in): 2.500 in.
Outlet Quantity: Single
Outlet Location: Center
Internal Construction: Glass-wrap perforated tube
Muffler Material: Steel
Muffler Finish: Aluminized
Case Length (in): 14.000 in.
Overall Length (in): 19.000 in.
Thickness (in): 4.500 in.
Width (in): 9.750 in.
Outlet Style: Standard, without tip
Quantity: Sold individually.

Muffler, Ultra Flo Welded, 2 1/2 in. Inlet/2 1/2 in. Outlet

NICEHATCH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h22aBB4 &raquo;</TD></TR><TR><TD CLASS="quote">do a search, i think in the faqs there is a section about backpressure. despite popular belief, back pressure will not help horsepower. jw- why do you say your car can get at least 209 horsepower? why not a nice and round number like 210? </TD></TR></TABLE>

Lol...lmao. ALright fine next time out. I'm gonna shoot for 210whp!

A Blue Lude

Worth seeing the graph, but I really doubt it was the exhaust changes that did anything. I'd want to say it's just a "different day" syndrome, although I probably don't have enough experience to make that call. I have been through it though

Run 2: h22a4, sms header, cat, 2.5" magnaflow muffler thingy. All the usual prelude stuff still attached.
A month and some later...
Run 4: same except with a 3" dynomax super turbo.

Theoretically a slightly more restrictive exhaust, but that would be seen at the top end only.



I figured it was either "different day" syndrome or engine damage from insano top-end AF ratios and timing values...but the motor made 182/143 a few weeks later on with a proper tune after an hour on the dyno (and a cheating open air intake pipe, but nothing drastically different), so the engine was probably still okay.

Just my 2c though.

h22aBB4

this may be completely wrong- but ill risk getting flamed lol. Maybe it was a really good tune with the parts before you did bolt ons, then the new parts negated that tune?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NICEHATCH &raquo;</TD></TR><TR><TD CLASS="quote">Lol...lmao. ALright fine next time out. I'm gonna shoot for 210whp! </TD></TR></TABLE> Thanks- ill sleep a lot better now lol

rawNArsxS

where in ny r u? whered u get it tuned?

GoldLudeRay

too me the curve looks almost the same
i geuss just diferent day.
and there is a certian amount of back pressure that every engine needs otherwise drag cars would run open heads......meaning you see the exhaust valves.


but this is such a slight change in backpressure i cant see it being the reason for your loss of hp

but on a postive note ur making perty good power on ur set-up

NICEHATCH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rawNAprelude &raquo;</TD></TR><TR><TD CLASS="quote">where in ny r u? whered u get it tuned?</TD></TR></TABLE>

I got the car tuned @ T&R Performance in queens.

mgags7

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by The Phil &raquo;</TD></TR><TR><TD CLASS="quote">

Bahahahaha. *points and laughs*</TD></TR></TABLE>

LOL

NICEHATCH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GoldLudeRay &raquo;</TD></TR><TR><TD CLASS="quote">too me the curve looks almost the same
i guess just different day.
and there is a certain amount of back pressure that every engine needs otherwise drag cars would run open heads......meaning you see the exhaust valves.


but this is such a slight change in backpressure i cant see it being the reason for your loss of hp

but on a postive note ur making perty good power on ur set-up
</TD></TR></TABLE>

I didn't post up the dyno-graph showing the loss in power yet. I believe you are confusing it with the insert by user: <U>A BLue Lude</U>. I will post up my sheet in a day or so and maybe someone can point out something.

h22aBB4

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GoldLudeRay &raquo;</TD></TR><TR><TD CLASS="quote">
and there is a certian amount of back pressure that every engine needs otherwise drag cars would run open heads......meaning you see the exhaust valves.
</TD></TR></TABLE>
hmm it doesnt seem like it would be a good idea to have all ur hot exhaust gas expelling right over the engine so the intake can pick it up

skunked

nice numbers. Now get some cams and move that power band up another 1K rpms

mgags7

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by skunked &raquo;</TD></TR><TR><TD CLASS="quote">nice numbers. Now get some cams and move that power band up another 1K rpms </TD></TR></TABLE>

yuppp

117

Backpressure? You don't need no stinking backpressure. I think my engine has about as little backpressure as you can get without running totally open header.

Here's plot of my dyno from having the engine re-tuned by Tony Palo this past weekend (sorry for the pic, scanner is broken):


Yes, I realize it's WHP vs. land speed. The RPM pickup wasn't working correctly at high RPMs, so the graphs look crazy when plotted against RPMs.

EDIT: It's uncorrected. The SAE corrected numbers are right around 204WHP and 154WTQ. When the engine was fresh, it put down almost identical numbers on a different dynojet.

For those interested, here are the specs of the car:
98 H22A4
AEM CAI
SMSP header
Euro R TB
Portflow valve springs
Open exhaust with a Coast Fab muffler - 2.5" core, 2.5" inlet, 3" outlet. The muffler is located about 12 inches from the collector on the header (almost directly under the shifter assembly), from the muffler it's 3" tubing around the gas tank with a turn down right in front of the rear control arm
STR cam gears (cam timing set to stock specs)
milled head
mild "polished" head (just removed casting marks)
3 angle/radius valve job
port matched IM
lightened crank
balanced crank, rods, and pistons
no balance shafts
no AC or PS
NepTune RTP P28 ECU

stock parts: valves, cams, pistons, rods, IM, injectors, and crank pulley

skunked

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 117 &raquo;</TD></TR><TR><TD CLASS="quote">Backpressure? You don't need no stinking backpressure.
</TD></TR></TABLE>

Nice graph, killer numbers for a OE H22 internals

Missing Gears

want to gain the power back that you lost + some???

get rid of the pos short ram and get some cold air going into the motor.

cold air=more HP

the 2.5" exhaust is fine as long as it is straight through and doesnt bottleneck anywhere.

117

Thanks. I was surprised myself. When it was fresh it made the same numbers, but right now, the cams have some scoring on the exhaust VTEC lobes and the valve rockers are slightly scored as well. It ticks like mad at idle. I had to go get it retuned as part of a trouble shooting process before I tore into the engine.

You should see the torque graph, it's actually quite flat.