Well **** me! This is going to be just me ranting...
So lets see here...originally I ran a 14.90@91.90 MPH with I/H/E.
A shift from 1st to 2nd put me at 4100 where I was happily making 96 WHP and 123 TQ.

Cams - $700
Skunk2 manifold - $300
S-AFC (to be able to idle) - $300

So now my powerband shifted upward around 500 RPMs..and although I gained 15 WHP and 20 TQ at redline...it didnt do me any good really since now when I shifted I made 8 less HP and 9 less TQ!
So I ran a pathetic 14.9@92.9 MPH.

Fast foreward another $700 for GSR gears and a lightweight flywheel...
now the car boggs 2nd gear after a shift to 2nd..and ran a 14.92@93.46 MPH.


Its so damn frustrating!!!
The cams, manifold, GSR gears and flywheel should all have helped..but now I feel like I have a "bottleneck" somewhere! Things just arent working together as they should.
Theres more power...but in the wrong areas!

Im hoping that the bottleneck is the low redline..and spinning the motor to 8000 RPMs will bring everything together.

Alright..Im dont crying like a little bitch now.

 

It will be ok, i promise!!!

 

why do you say your car is slower? You are running basically the same ET but with a higher MPH. You just need to get used to driving it again

 

Consistently bogs, or just on that one run (14.92@93.46 MPH)?

 

use the cam gears to move your power band!!!!!! That's the beauty of cam gears!!! You can move your power band to the midrange!

 

do you even have cam gears? cams by themselves without tuning are worthless!! I was looking at your dyno plots and I don't think your car is properly tuned! I see you lost midrange after installing the cams. You shouldn't have lost power anywhere, specially as much as you did.

 

I think I lost midrange because of the Skunk2 manifold..not the cams.
The powerband looks typical after switching to a Type R/Skunk2 manifold.

I do have cam gears but the yare at 0,0 now..Ill be tuning them Saturday.

 

u need some vtec my friend...haha, j/k

get the gears tuned, get some drag radials, and wait till its cooler out

 

hes exactly right......you have to tune w/ gears.....or else you get exactly what just happened to you.....get some gears and dyno time, and get your selft some more midrange.

 

How much dyno time was spent tuning these new parts?

 

Well...as I said the cam gears have not been tuned yet. The yare set at 0,0 right now. I have an appointment for 1 hour of dyno duning tomorrow - hopefully that will be enough time to tune them.

I spent a little bit of time tuning the S-AFC..but didnt realize much with that.
Gained 1-2 WHP at some points.

 

Welcome to the world of high performance parts With the much greater TQ and lower rev limit of the B20, you will probably find that the lower the RPM at which the TQ plateaus the faster the car will be. Peak HP is good if you have a light enough vehicle, but the greater the TQ spread the faster a heavier vehicle will be. If you can tune the power to approximate the same curve you had before (but with greater values), the vehicle should be faster.

Adding the GSR gears may not be as advantageous as it seems, since the gear spread is designed for a much higher revving vehicle.

 

Ultimately I would like to build the motor to rev to 8000..which should be able to take advantage of the cams, Skunk2 manifold and GSR gears.

Really the only issue now is 2nd gear...every other gear lands above 5000 RPMs (with shift at redline in previous gear).
Building the motor for a powerband of 5000-8000 *should* be the best for drag racing...sorrect?

Im kinda dissapointed now - but I think in the long run (8000 RPM shifts) it will all come together.

Thoughts?





[Modified by HX_Guy, 10:40 AM 8/24/2001]

 

If I remember right the drop from 1st to 2nd with the GSR gearset isn't as much as the drop with the LS trans, but...if your torque curve has moved up due to the higher rev limit you have, it may now be dropping you out of the 'sweet spot' of the curve. This will feel like a bog. You should be able to tune the cam gears to put the engine back into that spot at that new shift point. This phenomena is common with vehicles that have swapped tranny ratios, but use the previous tranny shift points.

One thing to remember too is that by short shifting (shifting at a lower RPM) you may be able to actually go faster than revving it out. This happens because after each shift the RPM drops back to the better torque spot, which is what really matters, not the HP.

 

GSR and LS 1st and 2nd gears are idential (ratios) so the RPMs fall at teh same spot - 4100 RPMs (not accounting for wheel spin)

The torque curve was moved "up" due to the Skunk2 manifold..not the revlimit..I havnt touched the revlimit.

 

So you didn't add the GSR final drive, only the gearset? So you're overall gearing in 1st and 2nd is the same as it was?

I guess what I meant to say was that given the same gearing, if the torque curve has been moved up the rpm band due to changes, you are now trying to pull a gear with less actual torque, which would account for the bog. I'm assuming by bog you mean an actual big drop in power, not just a 'softening' of power delivery.

 

I did change the final drive as well...bt the final drive doesnt dictate where the RPMs will fall in the next gear.

You see..the powerband has not been changed. The only changes made(recently) were the GSR gears and 7 LB flywheel.
The powerwand was moved "up" from the original stock dyno pull...but that isnt my concern.

The concern is...why, with the same powerband...and the same 1st to 2nd gear upshift "landing" point is 2nd gear bogging now and previously it didnt?
I do encounter more wheelspin (an additional 100 RPMs of wheel spin) now compared to the LS gears (due to the different final drive)..which could be why the big happens.

Am I making any sense here?

 

OK that is a little clearer. The powerband is the same, just that now with the GSR gears you have a bog when shifting to 2nd. I'm thinking it may not be the gears, but rather some other variable. Obviously it would be beneficial to see if it does the same if you put the LS gears back in there, but that's a lot of work to test a theory.

I wonder if it has to do with the reduced rotational mass of the flywheel? Since the flywheel has reduced mass, it would not be able to store as much energy as the stock flywheel. So when you shift and the RPM's drop, you have effectively reduced the amount of energy it is storing, allowing the rotational inertia to drop. This could be felt as a bog.

I remember when Honda introduced their oval piston Gran Prix bike years ago, it would actually quit running between shifts because they reduced the flywheel weight so much.

 

Yep...either the flywheel..or the increased wheelspin (from the shorter FD)

I was also thinking about the fact that the flywheel might not be storing as much power therefore it doesnt have the same "punch" when I go into 2nd.

Another theory is the increased wheelspin.
With the LS gears/stock flywheel a shift from 1st to 2nd at redline would induce wheelspin until around 5000 RPMs...at which the tires would hook up..and the car would accelerate to 7000 RPMs. While th tires were spinning, I suspect that the vehicle speed was also increasing...so whe teh tires hooked up..the engine RPMs matched the MPH...make sense?

Now with the GSR gears/7LB flywheel..a shift from 1st to 2nd induces wheelspin to 6000 RPMs (instead of the previous 5000). The car speed is still increasing..but cant keep up with teh RPMs...so when the tires finally grip...the engine RPMs dont match the car's MPH...and one must give. Naturally the engine RPMs drop to match the car's speed...make sense?

So what is the solution to this? Many have said stickier tires...so that 2nd gear doesnt spin as much.

The other problem is...I dont want 2nd gear to have ZERO wheelspin.
If I were to use slicks...2nd gear would not slip at all..and teh RPMs would land smack at 4117 RPMs..which sucks!
Ideally I would want some wheelspin..so the RPMs end up at around 4700-5000 RPMs. Hopefully some Drag Radials will give me what Im looking for.
Or as said previously...a higher redline + slicks...
A shift at 8000 RPMs with zero wheelspin in 2nd would result in 4700 RPMs in 2nd gear - perfect

 

Yes that sounds about right.

But, ideally you don't really wants the slicks to spin as spinning means you are not accelerating as fast as if the tires were planted. Typically some spin is OK but too much will only lower the speeds and increased the ET.

Slicks would certainly add traction, but like you said, until you can raise the RPM limit to end up in the zone outside of that 'soft' spot, it might be worth it to shift at a slightly lower rpm to see if the wheelspin is reduced.

 

Prolly the skunk2 mani... I say that $2,000 would have been better spent on turbo my friend.

 

u'll get ur power soon.. i just know it

 

Yeah I hear ya on that one, I was just waiting for someone to say it, or else I was gunna HEH

 

Wow! Where could I have gotten a turbo for $1600?!