As the topic states, My moderately built LS/VTEC engine is not crossing over into vtec like I think it should and I can't really figure out why. The engine set-up is:

B18A block, crank & rods (ARP rod bolts)
P30 pistons 0.25 oversized
New B18A bearings
New ITR oil pump, water pump & T-belt
Complete bottom end balancing

2000 GSR head (stock valves)
Blox Type B camshafts
STR Cam gears
Full Portflow valvetrain
Blox IM & 65mm bored TB
ITR intake tube and air box (stock)
RMF narrow style header (RMF )
STR fuel rail and B&M FPR
Cyl. head is also fully port-matched

US spec ITR tranny with Quaife LSD
ACT heavy-duty 6-puck clutch
ACT 8.8lb pro-lite flywheel

Comp. is a little over 12.0 to 1 and the engine has been base tuned at 13.3 to 13.5 AFR straight across with a P28 ecu, Hondata S100 (custom chip) and 310cc RC injectors.

The motor is very healthy, compression is at 260psi and even across the cylinders. It put down 192 whp and 127wtq on a Mustang dyno. It makes 137whp before Vtec and feels great in the low end. The problem is that vtec has been set very high at 6300rpm and still drops off huge, about 12whp, when vtec kicks in. Basically, the engine has a pretty bad bog, where I thought it would be creating quite a bit more power (a little over 200whp would be nice).

I will post pics of my engine setup and the dyno sheet for you guys, as soon as I figure how. Any help or suggestions are all appreciated. Thanks in advance - Mike


Modified by EGgsrAM at 3:20 PM 11/7/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EGgsrAM &raquo;</TD></TR><TR><TD CLASS="quote">
ITR intake tube and air box (stock)

Is my stock ITR intake tube and box a restriction?</TD></TR></TABLE>

The intake is hurting you..

 

What intake do you suggest? I have been thinking about a custom 3" cold air system made from aluminum bends or maybe even the AEM ITR system if I have the extra cash. How much do you think swapping intakes will help the boggy top-end?

 

get a velicity stack, and put it on your itr intake arm w/ a k&n filter

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EGgsrAM &raquo;</TD></TR><TR><TD CLASS="quote">It put down 192 whp and 127wtq on a Mustang dyno.

(a little over 200whp would be nice).</TD></TR></TABLE>

ummmmm....don't Mustang dyno's read lower than dynojet's? i think that you are making over 200whp, buddy. trust me, your numbers are good.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B16C1 &raquo;</TD></TR><TR><TD CLASS="quote">

ummmmm....don't Mustang dyno's read lower than dynojet's? i think that you are making over 200whp, buddy. trust me, your numbers are good.</TD></TR></TABLE>

Thanks for your comment. I'm am happy with the overall power that my motor makes but I feel there is alot more power to be had with this set-up, especially in the mid -range where my real problem is.

I'm trying to figure out why I have such a massive drop off in power after vtec engages. There is a 12whp drop at 6300rpm, I hope to have engine pics and the dyno sheet up soon so you can see the drop on the graph. I have seen several other very similar builds with lower vtec x-overs (5800rpm) than mine climb in power after vtec. Right now you can feel a really bad bog at the vtec point. This is what I need a little help to figure out. I want to know what I need to do to make my motor hit harder when vtec engages. I know someone knows.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ALLMOTOR18 &raquo;</TD></TR><TR><TD CLASS="quote">

The intake is hurting you.. </TD></TR></TABLE>

I am looking to replace my intake very soon, thanks for your suggestion. Is there anything else I should do?

 

You even said yourself "the problem is VTEC is set very high". Have you even tried lowering activation to 5800 RPM yet? That's the first thing I'd do. If I'm not mistaken Blox B's are similar to Skunk Stage 2's, which tend to like VTEC high, but not 6300. I'd try 5800 RPM because that's what I used to have my Skunk's set at .

And I highly doubt the intake would cause the car to bog that badly. I had a stock Civic intake on my cammed stock compression GSR and it still made 180 HP.

 

get some twm itbs!

 

Mike i told u, go 2.0lt you'll never have a problem at vtec. Sam

 

post the sheet

 

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

yeah, i would like ro see the 12 hp loss at VTEC engagement your are talking about....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by paopao &raquo;</TD></TR><TR><TD CLASS="quote">You even said yourself "the problem is VTEC is set very high". Have you even tried lowering activation to 5800 RPM yet? That's the first thing I'd do. If I'm not mistaken Blox B's are similar to Skunk Stage 2's, which tend to like VTEC high, but not 6300. I'd try 5800 RPM because that's what I used to have my Skunk's set at .

And I highly doubt the intake would cause the car to bog that badly. I had a stock Civic intake on my cammed stock compression GSR and it still made 180 HP.</TD></TR></TABLE>

Vtec was lowered during tuning to 5800rpm and the bog was even worse. My tuner told me we needed to raise it to get rid of the dip in power. It seems that in order to erase the dip, vtec would need to be set at around 6700rpm or so which is just stupid if you ask me.

I also agree with you that an intake would be hard to blame for this bad bog. But, I will be trying a 3" system soon.

Something else is wrong here and I'm determined to figure this out. - Mike

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eg2.0dart &raquo;</TD></TR><TR><TD CLASS="quote">Mike i told u, go 2.0lt you'll never have a problem at vtec. Sam</TD></TR></TABLE>

Sam, As nice as a 2.0L would be, I just finished this motor 5 months ago and I would prefer to figure this out and not just start building another motor unless I really have to. Give me a call soon, I need your help posting up my engine pics and my dyno sheet for all to see. - Mike

 

cam timing

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PURPLETERROR aka BIGMATT &raquo;</TD></TR><TR><TD CLASS="quote">cam timing</TD></TR></TABLE>
What do you mean by this: cam timing simply of the distributor? the cam timing my tuner put into my ecu program? or cam timing on my cam gears? Too high or too low? Please tell me a bit more about what cam timing you mean. Thanks - Mike

 

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

I also agree with you that an intake would be hard to blame for this bad bog. But, I will be trying a 3" system soon.
</TD></TR></TABLE>

Until this summer I would have absolutly agreed with this. Fortunatly I found out and intake makes a HUGE different. Heres the story:

91 crx jdm gsr vs 90 ef hatch ls/vtec CUSTOM INTAKE GOING TO HOLE IN BUMPER.


So we raced a few times,we were pretty even by the end of 4th gear. each of us had a passenger. few weeks later 90 ef hatch puts on a AEM CAI(nothing else had changed). I say we go to the perimeter and take a rip with the new intake.. I WALKED HIM LIKE HE WAS STANDING STILL. He put on the custom intake he had, and we were pretty even again. And to that day, I think intakes make a difference.

 

Thanks for your post z6. I will be putting a better intake system on my motor very soon. I also did a search on the AEM ITR system and found dynos on an all-motor set-up making very impressive results over stock and the famous J's racing intake. Check out this thread guys, I thought the results were amazing. https://honda-tech.com/zerothread?id=1194241

 

maybe whoever installed the cam screwed something up... (worn vtec lobes or possible damaged) especially if itwas used cam.

 

Bump. I hope you guys have a few more ideas or suggestions.

 

Alot of it may be the cams you are using.
Ill talk to the owner of the car, but i have a dyno of a car with a comparison of the tuner b's and the buddy club 3+s and the tuner bs made like 8 more top end whp after 7500 but in the mid range was destroyed by the buddy clubs by 5-10 whp across the whole range up to 7500.

tuner b's like HIGH vtec engagement, your tuner is right.


-s

 

Dyno sheet and a few other quick pics of my set-up have been taken. Special thanks to my friend Sam (eg2.0dart) who will be posting them up for me very soon. Let me know what you guys think; all comments welcomed.

 

did you get those pix up yet?

 

No pix yet, I'm having some camera issues. Once I get things figured out I'll post up the pics. Sorry guys, hope to have them working soon.

 

that intake is hurting you