383 sbc first dyno experience

[skinny z]

Issues aside Steve, it seems you've achieved your "ten something" goal.
Well done.

[PRH]

I’m sure you’ve already played with some ET/MPH calculators.......

Using 3650lb as the weight, the Moroso calculator shows to go from 119 to 121.3 requires about 30hp more.

Be interesting to see how that progresses along.

[steve cowan]

Leading up to Saturday there is always a comedy of errors, we hurt fuel pump on dyno so I fitted a holley 225 alcohol mechanical pump so then there were some fuel pressure fluctuations, then the autometer fuel gauge dampner packed it in.
The carb has a rich transition/ main jet where AFR are down to 11.0.
At WOT the AFR is 12.3 spark plugs looked fine.
As said I set timing a few degrees lower.
I am able to borrow a brand new XP 850 so I will run it on the street and see how it goes.
I think it is capable of going high 1.4s in the 60 ft.
I figured it would of run 123 mph first time out but there is a few issues, lash and cut open oil filter yesterday and everything looks good.
I was a little disappointed but always things can be worse.
Appreciate everyone contributing.

[PRH]

I tell people all the time....... you gotta start somewhere.

You started out with the new combo exceeding the old combo....... could have been worse.

What spacer did you end up using?

[steve cowan]

I tell people all the time....... you gotta start somewhere.

You started out with the new combo exceeding the old combo....... could have been worse.

What spacer did you end up using?

2" 4 hole no taper mis matched to carb pad on manifold, showed the best torque/ power / lambda
But I won't be surprised with a carb change the spacer deal could also change.

20220512_174837.jpg

20220512_174551.jpg

The open 2" lost 15hp on dyno but might be worth revisting ??

[steve cowan]

For anyone interested,
Have ran car over last few weeks.
Had a run tonight.
New 255/60/15 R series radials.
Backed up cam timing 4 degrees so cam is straight up 109 - 109 .
Car responded with a mph increase to where it should be .
I have my 950 hp (750) back on as well,still rich will be taking some fuel out for next meeting.
AFR from dyno were 12.3 :1.
At the moment it is 11.4 :1.
Plugs show rich at WOT.
34 DEGREES of timing.

20220730_163643.jpg

Still turning tyres off the hit as shown in the 60ft

[HQM383]

For anyone interested,
Have ran car over last few weeks.
Had a run tonight.
New 255/60/15 R series radials.
Backed up cam timing 4 degrees so cam is straight up 109 - 109 .
Car responded with a mph increase to where it should be .
I have my 950 hp (750) back on as well,still rich will be taking some fuel out for next meeting.
AFR from dyno were 12.3 :1.
At the moment it is 11.4 :1.
Plugs show rich at WOT.
34 DEGREES of timing. 20220730_163643.jpg
Still turning tyres off the hit as shown in the 60ft

Well done Steve. . 3600lb streetable car in the 10's with more to come using under 190cc sbc head and under 2" int valve. No mean feat.

Difference of .9 AFR from dyno to track interesting.

[408 Nova]

For anyone interested,
Have ran car over last few weeks.
Had a run tonight.
New 255/60/15 R series radials.
Backed up cam timing 4 degrees so cam is straight up 109 - 109 .
Car responded with a mph increase to where it should be .
I have my 950 hp (750) back on as well,still rich will be taking some fuel out for next meeting.
AFR from dyno were 12.3 :1.
At the moment it is 11.4 :1.
Plugs show rich at WOT.
34 DEGREES of timing. 20220730_163643.jpg
Still turning tyres off the hit as shown in the 60ft

You've done your homework no doubt. Nice work!

You get that baby to hook up, it's really going to run.



It seems to me that if the open spacer lost some on the dyno, that it would lose on the dragstrip also, assuming the same engine speeds. However, damned if I wouldn't try it.

[BobbyB]

For anyone interested,
Have ran car over last few weeks.
Had a run tonight.
New 255/60/15 R series radials.
Backed up cam timing 4 degrees so cam is straight up 109 - 109 .
Car responded with a mph increase to where it should be .
I have my 950 hp (750) back on as well,still rich will be taking some fuel out for next meeting.
AFR from dyno were 12.3 :1.
At the moment it is 11.4 :1.
Plugs show rich at WOT.
34 DEGREES of timing. 20220730_163643.jpg
Still turning tyres off the hit as shown in the 60ft

Great job Steve! Please tell us your thought process behind the small head & small valve that you are using.

[PRH]

Based on the speed..... there’s still a couple tenths up for grabs.

Just keep picking away at it.

Any impact on the 60’ from moving the cam?

[skinny z]

New 255/60/15 R series radials.
Still turning tyres off the hit as shown in the 60ft

Are you liking the new tires?
I'm assuming those are the Mickey Thompson ET Street R Radial Tires 3553.
I'm in the market for 255/50/16's myself but M/T only offers the SS version in a 16".

[swampbuggy]

Hello Steve C. , Did you make the decision on the Camshaft spec.'s ? Great results ! it should carry the mail quite well Mark H.

[steve cowan]

For anyone interested,
Have ran car over last few weeks.
Had a run tonight.
New 255/60/15 R series radials.
Backed up cam timing 4 degrees so cam is straight up 109 - 109 .
Car responded with a mph increase to where it should be .
I have my 950 hp (750) back on as well,still rich will be taking some fuel out for next meeting.
AFR from dyno were 12.3 :1.
At the moment it is 11.4 :1.
Plugs show rich at WOT.
34 DEGREES of timing. 20220730_163643.jpg
Still turning tyres off the hit as shown in the 60ft

Well done Steve. . 3600lb streetable car in the 10's with more to come using under 190cc sbc head and under 2" int valve. No mean feat.

Difference of .9 AFR from dyno to track interesting.

I removed the towbar a couple of weeks ago and weighed car at track last week 3620 with me
Going back through my notes-
Last weekend test and tune car ran 11.07 - 121.36 with wheel spin 1.73 in 60 ft ,week before that it ran 10.97 @ 121.34 .
Looking back now when I ran 11.13 @ 118 last year with similar combo with 010 block the 950 hp carb jetting will end up around there.
Initially I set up 950 hp for last weekend-
Front- 82 MJ 79 PVRC using my 3 hole cast metering blocks
31 - block - 31.
The PVRC is drilled no jet.
Transfer slot jet - 69" x 4
Drives up return road around 15 AFR. idle is afr of 12.3.
7.5 powervalve in front rear is blocked. 31 squirter.
Rear is 88 MJ , 31 squirter.
WOT AFR was 10.8 and showed rich on plugs.
So for this weekend I dropped 4 x jet sizes all round which is approx 8% calculations on pin size.
Front - 78 MJ pvrc fixed 79.
Rear - 84 MJ
Plugs show rich WOT with afr of 11.4.
I am thinking of going down another 4 jet sizes depending on pin gauge calculations.
Thoughts ?

[steve cowan]

For anyone interested,
Have ran car over last few weeks.
Had a run tonight.
New 255/60/15 R series radials.
Backed up cam timing 4 degrees so cam is straight up 109 - 109 .
Car responded with a mph increase to where it should be .
I have my 950 hp (750) back on as well,still rich will be taking some fuel out for next meeting.
AFR from dyno were 12.3 :1.
At the moment it is 11.4 :1.
Plugs show rich at WOT.
34 DEGREES of timing. 20220730_163643.jpg
Still turning tyres off the hit as shown in the 60ft

You've done your homework no doubt. Nice work!

You get that baby to hook up, it's really going to run.



It seems to me that if the open spacer lost some on the dyno, that it would lose on the dragstrip also, assuming the same engine speeds. However, damned if I wouldn't try it.

The spacer deal is a real eye opener for sure,and I agree the open spacer is worth a visit.

[steve cowan]

Based on the speed..... there’s still a couple tenths up for grabs.

Just keep picking away at it.

Any impact on the 60’ from moving the cam?

Moroso slide says 540hp for the weight, as much as I like playing tune up I am close to just focusing on suspension tuning, I need to be able to run on unprepared track.cant tell changing ICL regarding 60 ft can't hook up at the moment but will get there eventually.
When I initially ran 121 mph over a few meetings it would cross the stripe at 6600 rpm and honestly felt like it was out of breath.
Moving the cam back has made a big difference 2 mph in the 660.
From 98. " mph to 100.77 mph.
Picked up over 3mph in the quarter.
I don't believe taking some fuel out at WOT would make the difference.
1-2 gearshift - 7000rpm
2-3 gears hit- 7500rpm
Stripe 7000rpm @ 124.65mph