Don Terrill’s Speed-Talk

lekid wrote: ↑Mon Oct 07, 2019 8:25 am My original cam might be "completely wrong", but it sure works pretty damn good right now. Engine made just a touch over 700hp on the engine dyno

You're over 100hp off, from "pretty damn good".
A competitive Dirt Latemodel 410" engine will make over 800hp, with a cam in the low 260's at .050", and has to run 50 lap races.

Stan Weiss wrote: ↑Mon Oct 07, 2019 9:40 am What is your weight, et and mph?

► 1100 - 700 = 400 - if greater than 700 this will be less than 400

► 350 / 50 = 7

► 65 * 7 = 455 HP

► 70 * 7 = 490 HP

► (400 / 350) * 50 = 57.14 HP per 50 shoot

Need to work on your math, Has your nitrous system been flowed?

Stan

?? Not sure i follow. I understand him to say 350 jetting actually makes near 400.
If you put in 300 jetting it would make 65 less or 335. 250 jetting would make 65 less again, or 270 hp. Thats 65 hp per 50hp jet increase up til 350 jetting, but then moving to a 400 jetting should have netted closer to 465 but hes saying it seems to only gain 30-35 hp or 435 hp. So engine isnt taking in more gas or its having issues expelling it which could be cam imo

CamKing wrote: ↑Mon Oct 07, 2019 10:04 am

lekid wrote: ↑Mon Oct 07, 2019 8:25 am My original cam might be "completely wrong", but it sure works pretty damn good right now. Engine made just a touch over 700hp on the engine dyno

You're over 100hp off, from "pretty damn good".
A competitive Dirt Latemodel 410" engine will make over 800hp, with a cam in the low 260's at .050", and has to run 50 lap races.

With heads and cam and bottom end setup for big hp nitrous?

Orr89rocz wrote: ↑Mon Oct 07, 2019 10:11 am With heads and cam and bottom end setup for big hp nitrous?

400hp is not big hp nitrous.
If you took a Dirt Latemodel engine, and converted it to run 1/4 mile drag, with 400hp NO2, it would make even more N/A power then it makes in circle track trim. Just the added .100"+ of lift would be worth a good chunk of power.

CamKing wrote: ↑Mon Oct 07, 2019 10:22 am

Orr89rocz wrote: ↑Mon Oct 07, 2019 10:11 am With heads and cam and bottom end setup for big hp nitrous?

400hp is not big hp nitrous.
If you took a Dirt Latemodel engine, and converted it to run 1/4 mile drag, with 400hp NO2, it would make even more N/A power then it makes in circle track trim. Just the added .100"+ of lift would be worth a good chunk of power.

Not saying 400 is big but he could be trying for 600 for all we know. Regardless, for a dedicated nitrous mill optimizing valve seats, header sizes, piston/ring pack sizes, bearing clearances, oil weights, chambers and cam durations and lifts would be different than for na engines and usually i would have thought would hurt power if dyno’d on motor alone.

Orr89rocz wrote: ↑Mon Oct 07, 2019 10:32 am Not saying 400 is big but he could be trying for 600 for all we know. Regardless, for a dedicated nitrous mill optimizing valve seats, header sizes, piston/ring pack sizes, bearing clearances, oil weights, chambers and cam durations and lifts would be different than for na engines and usually i would have thought would hurt power if dyno’d on motor alone.

He could be trying to add 1,000hp of NO2, for all we know. He's big on questions, but short on information.
Building an engine to be efficient on NO2, will make it less efficient off the NO2.
Building an engine to run 3,000 miles between rebuilds, for circle track racing, will be less efficient then building it to last a couple hundred 1/4 mile runs.

What info do you want?
It has 23deg low port heads (248cc intake runners) and it is at 13.1:1 cr. It has a 300-25 manifold with a nitrous plate that has been flowed by Steve Johnson and it is good to 600hp (my cubic inch would not allow that much to be sprayed).

We never ran less than 250hp of nitrous (at least not in the last 5 years). We gained 65ish hp from the 250 to the 300 jets and same from 300 to 350 jets.

Car has ran 5.46@126mph with the 300jets, 5.34@128.5 with the 350jets and 5.29@130.1 with the 400jets.

The goal to to try and spray 450 and maybe 500 next year. It is a 100% nitrous engine, never run on motor alone.

lekid wrote: ↑Mon Oct 07, 2019 1:41 pm What info do you want?

Along with the info you've given,
Valve sizes:
Rocker Ratio:
Intake Port Flow CFM @ .300",.400",.500",.600",.700",.800"
Exhaust Port Flow CFM @ .300",.400",.500",.600",.700",.800"
header size:
Current intake valve lift:
Current exhaust valve lift:
Current intake duration @.020", .050", .200"
Current exhaust duration @.020", .050", .200"
Current Hot Valve Lash (Int/Exh):
Current Intake Centerline:
Current Exhaust Centerline:

Here you go:
Valve sizes: 2.100/1.600
Rocker Ratio: 1.7/1.6
Intake Port Flow CFM @ .300",.400",.500",.600",.700",.800" - 211/259/297/318/327/332
Exhaust Port Flow CFM @ .300",.400",.500",.600",.700",.800" - no pipe: 152/187/213/228/237/243/247
header size: 2" step 2-1/8" into merge 4"
Current intake valve lift: 0.800
Current exhaust valve lift: 0.722
Current intake duration @.020", .050", .200" - 306/273/193
Current exhaust duration @.020", .050", .200" - 324/286/198
Current Hot Valve Lash (Int/Exh): 0.020/0.020
Current Intake Centerline: 110
Current Exhaust Centerline: 118

IMO, the current cam has too much intake duration, and not enough exhaust duration. Going bigger on the intake, will just make it less efficient.
Here's what I recommend
266/289 @.050"
.465"/.465" Lobe Lift
116 LSA

I also recommend changing to 1.7 rockers on the exhausts.

Hello Mike, you mentioned 410" Dirt Latemodel engines duration numbers, how much gross valve lift do those guys run ? and what is their peak RPM ? Thanks Mark H.

Mike, also curious as to how big of a carb. they run Thanks Mark H.

swampbuggy wrote: ↑Mon Oct 07, 2019 8:59 pm Hello Mike, you mentioned 410" Dirt Latemodel engines duration numbers, how much gross valve lift do those guys run ? and what is their peak RPM ? Thanks Mark H.

Mid .700's for lift in most cases. Some as high as .800"
Peak HP around 7k

Don't know what carb size most are running now.