36 replies to this topic

[basicgreen]

hi guys i have a  202 that made 145hp on the dyno at 4700..then it just rolls of.. dyno man said might be springs getting soft more we did run it.it got less and less..had on the dyno from basically day one from build and always drops of around the 5000 mark..going to be putting supercharger on soon and have head of and going to do springs.. my question is i have had my plugs at 50tho all this time with a vk dizzy and msd street fire box and msd ss coil do you think that the plug gap was way to big.???.never thought to look into the gap when was running.. plain on running about 30 with supercharger 

cheers for any advice    

[Dr Terry]

Hard to read. The word OFF has two Fs.

 

Dr Terry

[rodomo]

Is that all you have to offfffer Terry?

[I'm a Red Motor fiend]

Gap is too big. Are the springs new and matched to the cam i.e seat pressure and on the nose.
Have you had your head flowed?

[Bigfella237]

Could be any combination of about a hundred & one things!

 

Could be anything (or things) in the valvetrain, cam timing, ignition timing, voltage/coil/spark, fuel supply, intake/exhaust tract restrictions, temps, etc.

 

I assume you are watching the WBO2 readings and it's not leaning out?

 

Would need a ton more data and some history of the engine before anyone here could even guess what the problem might be.

 

It's a bit like saying "There's a funny noise in my car, what do you think it is?"

 

[basicgreen]

thanks guys

its a 208 blue bottom efi 12 port head..has vr v6 valves witch are a bit longer so springs were to..manifold is a/speed and a 570 carb  

head flowed 248hp and i must say that from 500 lift to 550 lift there was only .2 difference if i read it correctly..lost the email now

the cam is 35647 517 lift 245 dur 107 sep..10.4 comp ( a little less than i thought) 

the engine was new and it seems every dyno run (4)  it seams to run OFF at about 5000

we were only doing timing and afr most of time not dynoing for every bit of horse power  $250 a shot 

i am just thinking back that one thing that stayed the same was plug gap and just wondering if  that could  could have bean a cause 

thanks again

[Zook]

Haha, funniest thing I've read in ages. I didn't get any of it except that it could have been this Bean's fault.

Attached Files

•  20200711_184323.jpg   87.73K   6 downloads

[arrimar]

msd street fire box and msd ss coil do you think that the plug gap was way to big.???

Is it true MSD is code for My Spark Died?

[Oversteer]

If it didn't miss fire your plug gap has nothing to do with not making power.

 

Likely valve train or cam timing issue if afr's and ignition curve are sensible and efi and ignition system is set-up and working correctly.

[LC-GTR-1969]

I personally do not think the 50 thou gap is the culprit. I run 50 thou now with my JZED headed engine. It would help if you could upload a dyno curve- this will help identify the issue. 

 

My gut says spring pressure or other valve control issue but would need to see the curve. What exhaust system are you running?

[basicgreen]

 dyno fb.jpg   200.52K   6 downloads hope this works

[basicgreen]

thanks guys exhaust is pacemaker with 2.5 exhaust and hooker muffler.. new pipes to go on are cae 1/58 prim

and the dur on cam is 254  not 245

will be defiantly be doing springs

thanks again  

[lawn bowls]

if the cam is 254 @ 50 thats a very big cam maybe its noising over cause of not enough carby 

[basicgreen]

this dyno run we did back to back runs with 450 carb (132hp) then 570 brawler made 143 then gave it bit more fuel and made 145  but still rolled over 

thinking probably springs like the dyno man said and what has bean said here 

[rexy]

The dips in your power and torque curves appear to correspond to your AFR rising above 13. That early hole is going to make it shitty to drive unless it’s a strip only car.

[basicgreen]

hi think the dip  is the secondaries opening 

[rexy]

Should be able to rectify.

 

Your graph suggests the fuel side is still part of the problem.

14:1 under full load is getting a bit close to the edge. And it’s costing you power.

[basicgreen]

cheers Rexy will take it up with dyno man when i get it back on the road..( bloody virus) holding things up  

[skap]

May I suggest swapping it out for a bog stock LS1. 

 

That will solve your lack of horsepower issues.

[claysummers]

Black efi Holden six rated at 104kW @ 4400rpm from memory. You're getting same output at higher revs??

Sent from my SM-G973F using Tapatalk

[yel327]

This is a chassis dyno. Holden’s ratings are engine dyno but the VK is DIN so probably comparable to chassis dyno divided by loss factor.

[LC-GTR-1969]

May I suggest swapping it out for a bog stock LS1. 

 

That will solve your lack of horsepower issues.

 

All those litres of capacity, all the engineering and fabrication, only to make less then a mild 202 with a strata setup. Each to their own I guess. 

[LC-GTR-1969]

I am curious with whats going on with the rpm at 140kmh- the rpm drops from 5300rpm to 3740rpm but wheel speed is increasing... looks like the run has been recorded in third gear and shifted just after 130kmh?

 

Am I missing something?

[warrenm]

I am curious with whats going on with the rpm at 140kmh- the rpm drops from 5300rpm to 3740rpm but wheel speed is increasing... looks like the run has been recorded in third gear and shifted just after 130kmh?

 

Am I missing something?

I think you're right, something odd going on.