starting line EGT's and does close count

I am under the impression that at launch (5,000 rpm) that egt should be around 600*

Question is how close should individual cylinders be?

We have a SBC, roots blower, Hogan intake with port nozzles, not set back. I was told only way for us to get close was to install a dribble system.

Is it worth the trouble? Would we see any difference in performance?

200* to 800* spread at launch,

 

Way to much spread in egt temp. You should get them as close as possible by modifying the fuel delivery at idle. The closer the better the performance and the less likely you will be to hurt the motor. You cannot tune with the main jet unless the cyl temps are fairly close.

 

This can be a difficult question to answer. Dribblers will work, but might not be the answer. You need to look at blower placement. What kind of blower outlet you have, manifold design and compression ratio.
Having all the EGT's the same temp makes a big difference. The motor has better throttle response and makes more power quicker. If you have 1 or 2 cylinders with low EGT's, then the other cylinders are struggling to make up for the dead holes. It's been a while since I've had to work on a blown small block, but I would think you need to be no higher than 500 degrees at launch.

 

it's a Littlefield 14-71 helix
Hogan intake

not setback as we don't have the room

#2 is the coldest

but at peak temps all 8 cylinders are all within 80*

does moving the hat nozzles futher back help?
it's helix and only a small pie shape opening in front
our last run at launch
#1 598
#2 295
#3 490
#4 897
#5 864
#6 828
#7 805
#8 606

can we reverse feed it like a screw blower
use the ports to feed it and run k valve thru hat nozzles? would air get too hot?

 

I agree you should not have over about 500 deg. at launch. You can lower the temp. by richening the barrel valve giving more fuel flow at idle.
Just remember one thing always err of rich side.
This will not solve your problem with the spread in cyl. temp. however. I would have to know much more abour your fuel system to recommend how to accomplish this. Seems to me you might have two problems here. It would not take a lot to even the 5-800 cyl. out and lower the average temp. at launch but the 200 deg. cyl might have another problem. It could also have a mechanical problem unrelated to the fuel air mixture.

 

Fuel pressure has a lot to do with this also. if fuel pressure is too low, then changing jets and nozzles wont have much of an effect. I've seen where too low fuel pressure has just the opposite effect when changing nozzles or jets. I'm a firm believer in high fuel pressures. The higher the better.
Late model roots blowers are much more efficient than they used to be and they benefit from using the screw blower style spool valve. They allow more fuel at idle without changing the leakdown. You can get these from Enderle. I would start there.

 

Umm...wut's a dribbler system???

 

Dribblers are low pressure port nozzles. They "dribble" fuel at launch rpm to cool off the hotter cylinders.

 

TRIED YOUR DRIBBLER BACK IN THE MIDDLE 90'S IN OUR S/E PRO-OUTLAW SMALL BLOCK DRAGSTER!!DID'NT LIKE IT ,MADE THE CAR FAT OFF THE LINE..HAD ALL THE TEMP. AT 800 TO 820 ,HAD .940/.950 60FT.WITH A MIKE'S TRANS.& CONVERTOR..

 

Enderle sells a small check valve that installs between the nozzle body and nozzle jet.put them in coldest cylinders (stage). at w.o.t. the valve is open. you may have to play around with the spring pressures and they may have an affect on the other cylinders (volume change) but they do work

 

To further clarify the function of this check check valve - It will not be completely closed @ stage rather just offering some resistance in flow to that particular cylinder. our stage pressure at the nozzles is 25 psi or so.the check valves are at 10-15 psi.we use 3 of um.

 

Waterman makes check style nozzle bodies also. These are better than the Enderle's. You don't have to flow a Waterman as they are just about dead on. You never know what you get with Enderle.

 

orderd the port check nozzles from waterman Monday, plan to test on the 10th, will update

this is helping me alot, thanks to all

we use K.J. Crawford drop in jet system, they are flowed then stamped with the number

will check with him Monday and see if he has these nozzle check valves.
if not I will make other calls

unless someone has about 4 lying around they would sell

[ August 30, 2005, 09:52 AM: Message edited by: rickey ]

 

rickey

This may help you in adjusting your barrel valve to get more consistent idle temps. We have developed a tuning aid for adjusting your barrel valve by hand, with no tools, engine running or not, with repeatable detent settings. It is the result of our struggling with a stack injection system and inconsistent settings until verified with a leakdown tester. You can check your settings with the leakdown tester one time and then repeat your settings each time just by rotating the detent adjuster. Resolution for each click is equivalent to 1/2 flat on a typical hex link type adjuster and it will fit most types of barrel valves. Go to www.hadfordracing.com to check it out. My apologies to Will for not advertising on this site, but we've got to sell a few of these units first to be able to afford the ad rates......

pcf

 

Waterman checks may be more accurate but they are aluminum and corrode and stick on methanol. The enderle checks are brass and work far better. I am referring to nozzle body check valves. Herb Western Country racing

 

In all the years weve used them, we never had one stick. We always drained our fuel system and used a filter between the pump and barrel valve.