I changed from a Edelbrock Performer RPM to a Dart single plane manifold last weekend. Results from my initial round of testing can be read here (http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=4;t=021008).

Between last weekend and today I made the following changes:

- Installed a 50cc accelerator pump in the rear of my HP-950
- Went from .037 to .040 discharge nozzles front and rear
- Jetting remained unchanged at 79/86
- Still not running a carb spacer with the new intake

Previous outing the best 60' with the new manifold was 1.565. On that pass the car went 6.97@99.11 through the 1/8th in 3,557' air. Yesterday the car ran a 1.490 60' and 6.853@99.98 in 3,038' air. The change in discharge nozzles was quite dramatic. I'm planning to go up even further to a .045 or .047 in the rear discharge nozzle. Holley recommends a 50cc pump for anything larger than .040. I'm still running the stock 30cc pump in the front and likely won't change it. There is still quite a bit more in this new manifold with spacers, jetting and more refinement of the accelerator pumps. This thing is going to be nasty when the air comes around in the fall :cool:

For anyone interested I made it to the 4th round in the bracket race Saturday. The car count was fairly low. There were only 10 cars in the 4th round, so only 7 rounds total to win. I could have made it past the 4th round but I was slow on the tree with a 6.03 R/T :( At any rate, it felt good to go some rounds without having to buy back graemlins/thumbsup.gif

Hey Ken,

Glad to hear the tweaking is paying off graemlins/hurray.gif . Did you first make a baseline run(s) with the old carb setup at the track before swapping in the 50cc pump and larger squirters? It would be nice to know if the 60' improvement was 100% from just the carb tweaks or if improved track prep and the slightly lower DA had anything to play into the results.

Either way, that is a nice improvement in 60' qith simple changes...need to get out there and tweak the squirters in my 850 too...next time I guess.

Sure wish you would drag that thing out east and lets go run at Cecil or MIR this fall. graemlins/thumbsup.gif graemlins/waving.gif

FYI - There's an interesting article on Edelbrock manifolds in the July '04 issue of Hot Rod. Helped me decide what to buy/use on my street 400.

Todd,

No, I didn' do the pump conversion/squirter changes at the track although it would ahve been fairly easy to do so. I've got a PerformAire Eclipse weather station that I use to measure the air with. Over time I've managed to get 50+ runs in a few different databases with DA ranging from -1,000' to +4,250'. I'm able to accurately tell how changes affect the car using the information in these databases. The DA index for my car as calculated by the weather station is .019 per 200' in the 1/8th. So with good air and traction my car should be able to click off a 6.5x 1/8th. That sounds about right as from best to worst air with the old intake setup I saw .26 change in ET in the 1/8th (6.75 vs. 7.01).

Isn't the about 519 feet difference in elevation a good part of your doing better?? I ask b/c I'm not a fine-tuner guy...

B/c in Missouri, 500 feet drop's us down to within a couple+ a hundred feet of sea level..

pdq67

Originally posted by pdq67:
Isn't the about 519 feet difference in elevation a good part of your doing better?? I ask b/c I'm not a fine-tuner guy...

B/c in Missouri, 500 feet drop's us down to within a couple+ a hundred feet of sea level..

pdq67 In short, yes the 500' better air helped some, however it doesn't account for all the gain. As I posted above my car will see an increase of ~.019 for every 200' drop in air or ~.009 for every 100' drop. Therefore .049 in ET gain was due to better air. The remaining .071 was due to the changes that I made which resulted in quicker 60' times. The ET gains are easy to spot when you calculate the splits (60-330, 330-660, and so on). You'll find if you ever get heavily involved in bracket racing (or accurately tracking your car's performance) that repeatable/consistent testing is required to ascertain what effect a change you make has on the cars performance. Some of the many things that you have to be able to repeat are:

- engine staging temperature
- trans/oil temperature
- tire pressure
- launch RPM
- shift points
- staging procedure (where you are in the lights)
- accurate weather tracking (need to measure the air in the same place and at the same time before, during or after the run each time. This demands the use of a good weather station or accurate gauges)

Keeping this sort of routine and accurately measuring results requires a lot of attention to detail, something most people are not willing to do.

Also, remember that a car's performance isn't only affected by the track elevation. A car's performance is affected by density altitude, which is a measure of temperature, humidity, barometric pressure and dew point at a given altitude.

Ken,

Very interesting results. Thanks for posting.

I'm curious, did you ever try the pump/squirter changes on the Victor Jr.? Makes me wonder if you would have seen similar results.

Also, do you have any other passes (60' times) recorded with the RPM intake with similar DA to rule out track prep?

Regardless, it definitely looks like the new intake is making more power throughout the range. It looks like your personal best ET/MPH are in jeopardy when the weather comes around this fall.

graemlins/thumbsup.gif

Originally posted by DragRacer:
Ken,

Very interesting results. Thanks for posting.

I'm curious, did you ever try the pump/squirter changes on the Victor Jr.? Makes me wonder if you would have seen similar results.

Also, do you have any other passes (60' times) recorded with the RPM intake with similar DA to rule out track prep?

Regardless, it definitely looks like the new intake is making more power throughout the range. It looks like your personal best ET/MPH are in jeopardy when the weather comes around this fall.

graemlins/thumbsup.gif Hi Jason,

In all honesty I never did try any different squirters with the Vic Jr. However I did try a myriad of jetting and spacer plate changes over two separate test sessions. The Vic Jr. not only slowed in 60', but also didn't run any better MPH than the dual plane even in better air. In fact, it was slower at every increment of the run. It was at this point that I concluded that the Vic Jr. was too small for my engine. After removing the Vic Jr. I measured the cross sectional area of the runners only to find that it was significantly less than the dual plane Performer RPM that it had replaced. You see my RPM had been opened to a FelPro 1205 gasket and the Vic Jr. was a box stock piece that I never touched. I think that if I were buying another Edelbrock single plane that it would be the 454R CNC. It comes in two sizes, one for lower RPM BBCs and one for higher RPM applications. That little Edelbrock Performer RPM that I took off was tough! I have ran all my best #'s with it including the 1.46 60' (several of them). As you've mentioned those numbers will be falling when the good air comes ;)

What I have learned from the Dart intake is that my heads flow really well and can make use of the additional plenum area offered by the current intake. I'll tell you, for the money these little 310cc Canfield heads are hard to beat!

Yes, m thinking the same on those heads. Good stuff as usual Ken. I'm dying to learn, vicariously through you of course, how kjetting changes things, if at all.

Yes, it was a deliberate typo. ;)