No Go

With 1200 miles on the 381 and Mobil 1 in the oil pan...off to the dyno shop.

Did 6 pulls from 2000-6800 rpm tweaking AFR each time.

Best runs was #5 with 363 WHP and 323 WTQ.

Topend still layed down after 6350 rpm, but not nearly as a significant drop as before due to valvetrain problem.

I'm ecstatic! Why...Engine did not come apart! Ha.

I'm up 27 WHP from the modified OEM LT4. Little on the low side, but maybe a valve spring swap might gain some more rpm/power. Until then I will set my shift point at 6500 rpm and have fun.

And have fun at the track we did. Audi day today at local 2.2 mile roadcourse so in the afternoon I put the car thru its paces...Nittos are now bald, brakes faded, cut some grass (oops) and got the engine hot...275 oil and 215 coolant. Steering made a bit of noise, but did not falter.

The 11.9 compression and GM 847 cam really thump...talk about a killer idle...but watch out for the drivability below 2000 rpm. Still banging my head on that...

Time for One Lap of America-12 days and counting...:D

By the way, 363 WHP (on a MUSTANG 1750 dyno!) equates to ~455 Factory Rated Engine Horsepower or close to 400 on a Dynojet. :)




[Modified by No Go, 11:25 AM 4/17/2004]


[Modified by No Go, 8:42 AM 4/18/2004]

zelement

That's some great numbers for a Mustang dyno.

AGENT 86

:cool:
Good numbers :thumbs:

STL94LT1

Nice #'s, and good luck on the One Lap of America.

LTxDave

Awesome #'s. :hurray:

superlund

Nice work, good luck at the One Lap event!

:cheers:
-Jim

Corvette0096

:cheers:

ralph

What are the specs on that cam and what drivability issues are you having below 2000?

Good luck at the 1 lap!!!!!

Shriker

No Go, great post and interesting info as always.....you have done a great job chronicaling (is that a word? :confused: ) your car. I REALLY would have thought you would have picked up more than that with that cam/combo..... hmmm. Do you have a copy of the dyno sheet , I would love to see it.

You mentioned drivability below 2K, does it surge or have poor throttle response? How is partial throttle across the range?

Interestingly, this is the third stroker LT4 in the past few weeks (two 396's and your "383" ) with similar setups and ALL have been right around 400+ rhwp (on dynojet ;) ). Hmmmm.......

Good luck with the motor , great job , and keep us posted ....... will be pullin' for ya a the One Lap! :thumbs:

No Go

Thanks folks, figure some of my (in)experience could help others out :)

I'm trying to post the dyno sheet compared to the last combination, but some computer problems...it will be forthcoming.

A link to the Crane counterpart to the GM 847 camshaft is:
http://dab7.cranecams.com/SpecCard/D...B1=Display+Car

My GM part has the Crane identification etched on the front of it...so same, but I like GM parts, besides cheaper from Chris May than Summit...:)

My main goal was more topend power, but still usable on the street. More topend power was found, but the drivability issue below 2000 rpm could be a deal breaker for some. With the large camshaft, fresh valve springs with a bit more installed pressure, repaired cylinder head defect (allowing the springs to do hula hoop on the cylinder heads), and AFR Hydra Rev kit, I was really looking for a solid power band to ~6800+. After the event I will probably attempt an install of new CC Beehive springs...some reputable folks have achieved 1000 greater rpm with the change alone (I'm only looking for 5-600 rpm)

Drivability issues: the cams overlap apparently is not liking the 14.7 AFR the OEM computer demands. I can't change that with my LT1 Edit, but some have minimized the effects with more/less timing which ends up being a trial and error deal. Basically, the car has herky jerky/trailer hitching feel when running below 2000 rpm. Of course idling thru a parking lot at this rpm in 2nd gear you feel more of it than on the highway in 6th-there it is only barely perceptible especially when coming down a long down hill where the throttle is closed or nearly closed on cruise. Note that I have a Camaro single mass flywheel (17 pounds) and 3.45 gears, neither of which help a 'high speed' cam cope. Turning 1600 rpm in 6th on 400 mile road trip, the car returned 27 mpg average...so it does not kill the gas mileage, heck it will run smoother when you bump the rpm to 2000 rpm...which equates to ~90...hmmm might be good for OLOA...:) Once past ~2000 rpm, the part throttle drivability, feel, etc are exactly like stock. Seems like the MAF of the 96 adapts quite well. Throttle response overall is excellent. May be psychological, but the high CR makes it nearly race car rap quick. :) Sure is nice on those heel/toe downshifts...yeehaw!

My throttle body, mass airflow sensor, and cast iron exhaust manifolds with OEM cats are all original. I'm reluctant to swap those, maybe the TB in the future, due to emissions, durability, etc.

Someone else mentioned a link to OLOA to follow the results as they happen might be helpful...
http://www.onelapofamerica.com

And again, if anyone is interested in visiting the event at any of the tracks...admission is free...I just have to drop your name so you can get thru the gate folks. Free! Hardly even see a 1 year old Lamborghini going sideways on a dirt track...not this year, but still some very cool cars from around the world even.

Email me at tmcarthurs@hotmail.com

It will be a riot if it don't blow!

Raistlin

No Go, can you remind us what heads you're using and the specs on them?

thanks
--steve

Good luck at one lap!!!

Shriker

Holy Cow , No Go ....you are on original exhaust manifolds?!? 400+m rwhp with those on that combo is not bad at all......Headers alone would add 15-20+ rwhp on that combo. You should consider some shorties and high flow cats at least.....those would most likely save 20+lbs and gain at least 10-15 rwhp on your combo I would think. :thumbs:

crheinish

Very good information, thank you for posting it. :cool:

No Go

Cylinder heads are LT4 castings with Stage III CNC by CNC Cylinder Heads in Florida. The intake was ported to match the heads as well.

Flow is 280/187 CFM intake and exhaust at .550 lift on local flow bench. Not outstanding numbers for what I payed for, but not terrible either. They do seem to work.

Still unable to load a dynosheet-forum problems...sorry.

Raistlin

:thumbs: thanks for the great information. great numbers, too!

LT4POWR

Those are damn good #s considering the stock parts and a Mustang dyno. :thumbs: