Dyno'd my motor: HP sucks!

[Nuke427]

You stated you have a Cobra intake and 73mm intake tube. Do you also have a larger throttle body? My old car, set up similar to yours didn't pull very hard after 5k. I installed a Edelbrock RPM intake and it helped but not much. I then installed a Trick Flow elbow, didn't see any change. Then I installed a 70mm throttle body and the car not only pulled extremely hard to redline, you could hear the air getting sucked into the intake. It was the limiting piece in my setup. End result on modifications is as follows (Which pulled to redline hard)
RPM intake
RPM heads 1.90 valves
E303 cam
70mm TB
73mm TF elbow
30lb injectors
Crane 1.7 rockers
Pulleys
BBK headers
No cats.

[Excaliber]

13.9 at 107

He's got those slippery Goodrichs. He'll either send 'em up in smoke or bog out of the hole!

[DAVID GAGNARD]

Daren;

Coming back to your original questions......If you engine seems to "quit pulling" around 4k rpms,it very well may be your valve springs.... They may not have enough spring pressure to support higher rpms,also,stock heads even ported and polished are not the greatest...... If and when you decide to "upgrade" my suggestions would be a good set of A/M aluminum heads.......This will net you the most hp gain,then start fine tuning the other items,throttle body,intake tube,injectors etc,etc.,then you should see some higher hp numbers.......next would be exhaust system upgrade to match the better engine breathing capabilities.....

Still with your set-up it should run pretty quick.......

As far as the drags go,your tires are not the best,you will have trouble coming off the line at anything much more than idle without smoking the tires,but with some practice you should see low 13's,speed around 110 to 115 mph......

Hope you have fun at the drags;

David

[dameeks]

Man, you guys are good. Went to the track Friday night. I only got one run in, due to "technical difficulties" on the track (my buddy slammed his vette into the wall right in front of me, right before I was ready for my second run. he's fine, just some body damage to the car). So, here are my numbers:

Reaction: 1.08
60 ft: 2.07
330 ft: 5.61
1/8 ET: 8.57
1/8 mph: 83.51
1/4 ET: 13.35
1/4 mph: the track was screwed up on this, and didn't give me a number on my slip, but someone told me they heard 108, so I'll go with that

So, I'm pretty happy. 60 ft. time not too great, Reaction time not too great (neither very surprising, given it was my first time to ever even nail it from a dead stop). Wheel spin actually seemed pretty low. You know how it is, though, especially your first time: I couldn't tell you a thing about what happened. The adrenaline was rushing. I don't even know what rpm I was shifting at. Next time, hopefully I'll be able to pay a little more attention. Maybe with a little tuning, better tires, better shifting and I'll be in the 12s? One thing I did notice was that I didn't feel the power lag that I had mentioned before near the top. The car pulled hard the entire time. Again, my mind is pretty foggy about it all, so who knows what really happened?

One interesting note. I had the only Cobra at the place, and it was like I was a rock star. People couldn't have cared less about the 10 second Mustang in front of me. They only wanted to talk about my car. A nice feeling. Although, I couldn't help but laugh at the guys that would say this: "Oh, it's a replica? Well, it's still nice, though." As if to say that I shouldn't feel bad because it's only a replica. Anyway, they were all loving the car.

Nuke427: I'm honestly not sure what size throttle body I have. I'll find out. Did you ever have your car dyno'd with that setup?

David: May be a silly question, but is there any way to check the state of things such as the valve springs without ripping the motor apart?

Darren

[DAVID GAGNARD]

Darren;

You did well,I remember my first time at a dragstrip like it was yesterday.... When I pulled to the line and pre-staged my left leg/foot was shaking so bad I knew it would slip off the clutch pedal and kill the motor right there....Car on the side of me had open headers and when the lights started coming down he got on the gas,instictively I did too and did one of the best burnouts of all time when the green light came on,ran a 15.1,boy was I disappointed.....after three more passes I was down to the mid 13's and cutting a pretty decent light to boot..... it takes practice-practice-practice and forget there is a car on the side of you,run your race to your abilities and the abilities of your car and you'll do just fine........

You need to get in a "routine" when you get to the line and try to do the same thing everytime....My little routine goes something like this; after a small burnout,I do a "dry hop" to clean the tires,inch to the lights,just before pre-staging I stop and check all my gauges and when they all are o-k I pre-stage,after that I take a couple of deep breaths and stage,once staged,I watch my tach and the lights,when I see the last yellow light,I go,and watch the tach with one eye and the track with the other,shift thru the gears and when I get to forth gear then I usually have time to take a breath and glance to the side if the other car has not already passed me,once I cross the finish line I look for the win light on the gaurd rail,bump the trans in neutral and start getting on the brakes looking for the exit lanes.......It works for me and you will have to figure out what works for you,but that's half the fun....

You can check your vavle springs by pulling the valve covers,they do make a tool to check spring pressure with the heads on the car.... Also,push down on the top of each one with your thumbs,you should not be able to compress them,you ideally want around 120psi or a little more spring pressure on each one,I have found it takes at least 115 to 120 to keep the valves from floating at 6000rpms....On engines turning more than 6000 rpms I like to have 130 to 150 psi on my springs.......If you can get 120 psi you'll be o-k for a 6000 rpm street engine......

With some practice and "playing" with your rear tire air pressure you should easily get in the high 12's.......Good luck and have fun..........

David

[Excaliber]

OK then, MidOhasp wins the 1/4 mile time award and I get the trap speed award!

,,,,,as slow as it was you still got out of the hole quicker than I thought you would. First timers almost always blow it big time at the light. Not bad!

[dameeks]

I knew that if I nailed it at the line the tires would just go up in smoke, so I didn't totally get on it until i was moving a bit. Surprisingly, the tires seemed to actually stick pretty well. It's especially surprising because there was no way to avoid the water. You had to go through it, and then there wasn't a big area to do a burnout. So, i did about a 10 foot burnout and pulled to the line, hoping all the water had come off. Without having slicks, I figured it wouldn't do any good to heat them up. I don't have a line lock, so it would be tough anyway. I've also heard that you shouldn't heat up street tires, as they let out some kind of oil when they get hot. I'd like to get in a few more runs so that I can try some different ways of getting out of the hole.

David: I'll check out the valve spring pressure first chance I get. I figure if I can do enough of the little things, I can avoid spending big bucks on new heads and the other expensive goodies. I think the headers are gonna be a good $400 - 500 as it is, so every little tweak I can make on the cheap will help out.

Excaliber: I'll deliver your "award" in person, just as soon as I get over to Hawaii. Like half the people in the world, I went there on my honeymoon and certainly wouldn't mind going back.

Thanks,
Darren

[Nuke427]

dameeks,
I never had the car dynoed before I smashed it into a rock wall. I do remember that with that car I was bouncing off the 7k rev limiter quite often. Fast spin up with that setup.

[DAVID GAGNARD]

Darren;

One track I have run on does have a wide entrance to the tree and you can/could go around the water if you wanted,I always did,the other track you could get by with just one tire in the water box.... if possible running street tires you are better off NOT going thru the water and doing a dry hop to clean the tires before staging.......Street tires will work better if they are not real hot.....

A couple of other "tricks" you may want to try,lower your rear tire air pressure to around 20 psi and put about 50 psi in the fronts,help cut down on rolling resistance in the front.... If you plan to do a lot of drag racing consider buying a set of BFG Drag Radials,I did,that alone was worth about 4 tenths on my car..... Since I have a fairly high rear gear (3.00) for the highway,I bought a set of BFG drag radials that were only 24" tall compared to my 26" tall street tires,same as putting a lower rear gear in the car,they come in all sizes and hights...

David

[LwCwb]

you could put a supercharger on it.....

[DBLDREW]

First off the stock headers are junk you need to change them. I would contact Factory Five and find out if they make a full header option and go with this if it is in your budget. If you cant afford it (or they don’t offer it) there are a bunch of companies that offer a shortly header that will fit the oem mustang exhaust, BBK, JBA to name a few. This will much improve the exhaust flow over the stock header.


Another possibility that could be hurting you is your heads. I have a 89 mustang that I pulled out the 302 and put a 351 that was pretty built up. But I was running a little low on funds so rather then buying a new set of heads I just had my stock 5.0 heads ported and polished and new valves put in. Well the car didn’t run the way I thought it would, I never had it on a dyno but the best time at the track was 13.60 @104 mph I had the same problem that you are describing it would pull strong but start to drop off around 4500 rpm. Well after a ton of diagnostics I figured that it must be the heads and I opted to bite the bullet and buy a new set of heads. I bought the Performer RPM heads (this was about 8 or 9 yrs ago so I didn’t have the AFR option) Well after I bolted them up it was unbelievable how much more powerful the car was. With no other changes other then the heads I went from a 13.60 to a 12.40@ 113mph! So the guy that did my port job obviously didn’t know what he was doing.

I’m not saying that you should go out and buy new heads yet (that’s a very expensive experiment) but maybe try the headers first and see if it improves things. It’s possible that the guy that did your port job knew what he was doing and they will work fine.

Also some one else made a comment about an E-303 vs. a B-303 cam. I would be very careful with switching cams. If the heads you have do actually have 2.02 valves there is a potential valve to piston clearance issue. I believe that if you go with a cam that is much over .500-inch lift you will need to fly cut your pistons. I don’t know off the top of my head what the lift is of the E-303 I do know that the B-303 is .480 and is in the save zone.

Anyway good luck.