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340 pump gas stroker tests, guess results for tomorrow?

Posted By: Cab_Burge

340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 02:57 AM

I'm engine dyno testing a 4.0 inch stroke 340 motor with a 4.070 bore (EDITED blush) and 10.41 to 1 compression ratio with a Quikfuel 830 CFM black carb with down leg boosters. The heads are a set of eddy RPM and a Eddy Performer Air gap intake. All testing was done with Oregon 92 octane non ethanol pump swill bought this morning. We had to fight ignition and carb. issues this morning so we didn't get to make a lot of pulls today runaway We did make two, first one was from 2500 to 5000 RPM and it made 440 HP at 5000 RPM after running it over 30 minutes total time to break in the cam and lifters. We let it cool down so the oil temps were under 150 F and made the next pull from 3000 RPM to 5500 so we could see If the torque and HP curve crossed at 5250 RPM, which it did up On that pull it made 447 HP at 5000 RPM and 459 HP at 5200 RPM with 514 Ft. Lbs. torque at 4300 RPM boogie
I've seen SB Mopar NHRA legal stocker motors take 6 to 12 pulls before they stop gaining power on the dyno confused
Tomorrow will be a short day testing jetting and timing only, who wants to take a guess at peak torque and peak HP work
All guesses welcome, no rewards so no favors tsk grin
I'll post the results as soon as I can tomorrow evening so bear with me please.
Posted By: justinp61

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 03:11 AM

4.370" bore" ?
Posted By: Twostick

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 05:16 AM

Pretty light for 480 inches... laugh2

Kevin
Posted By: Cab_Burge

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 06:22 AM

Me thinks 4.0 stroke with a 4.070 bore(EDITED blush) = 416 C.I. shruggy
The last race 471 C.I. BB I built and dyno made 720 HP at 7000 RPM and was still gaining 2 to 5 HP per 100 RPM, the customer swore he would not rev it past 7000 RPM so he had us stop their shruggy
HP is not hard to make, paying for it can be work shruggy
Posted By: CSK

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 06:41 AM

Cab Check your #'s on bore & stroke
Posted By: 360view

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 12:48 PM

493 horsepower.

2 sparkplugs will show signs of detonation.

Some injury while wrenching will cause at least one drop of blood to flow.
Posted By: justinp61

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 02:47 PM

Originally Posted By Cab_Burge
Me thinks 4.0 stroke with a 4.370 bore = 416 C.I. shruggy
The last race 471 C.I. BB I built and dyno made 720 HP at 7000 RPM and was still gaining 2 to 5 HP per 100 RPM, the customer swore he would not rev it past 7000 RPM so he had us stop their shruggy
HP is not hard to make, paying for it can be work shruggy


Me thinks if it's a 416 with a 4" stroke the bore is 4.070".

I'm guessing the cam is small for a stroker? Was the QF carb rich out of the box? The ones I've messed were pig rich as delivered.

Should be a fun driver.
Posted By: Cab_Burge

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 04:21 PM

Originally Posted By csk
Cab Check your #'s on bore & stroke
up Thanks for pointing out my error blush
Posted By: Grizzly

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 04:47 PM

470 hp
520 tq
Posted By: RapidRobert

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 04:53 PM

Quote:
All guesses welcome, no rewards so no favors tsk grin
I'll post the results as soon as I can tomorrow evening so bear with me please.
Cab you sound pumped. I'm glad it is (nearly) finished & going well, enjoy it!
Posted By: Paul_Fancsali

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 05:04 PM

493HP possibly 505hp with better gas
Posted By: fast68plymouth

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 05:32 PM

Quote:
.....and made the next pull from 3000 RPM to 5500 so we could see If the torque and HP curve crossed at 5250 RPM, which it did.....


The curves will always cross at 5252.
HP and TQ are exactly the same at 5252 rpm.
Posted By: Guitar Jones

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 07:30 PM

Originally Posted By fast68plymouth
.....and made the next pull from 3000 RPM to 5500 so we could see If the torque and HP curve crossed at 5250 RPM, which it did.....

The curves will always cross at 5252.
HP and TQ are exactly the same at 5252 rpm.


Horsepower is a matter of calculation from torque.

Quote:
To get from pound-feet of torque to horsepower, you need to go through a few conversions. The number 5,252 is the result of lumping several different conversion factors together into one number.

First, 1 horsepo­wer is defined as 550 foot-pounds per second. The units of torque are pound-feet. So to get from torque to horsepower, you need the "per second" term. You get that by multiplying the torque by the engine speed.

But engine speed is normally referred to in revolutions per minute (RPM). Since we want a "per second," we need to convert RPMs to "something per second." The seconds are easy -- we just divide by 60 to get from minutes to seconds. Now what we need is a dimensionless unit for revolutions: a radian. A radian is actually a ratio of the length of an arc divided by the length of a radius, so the units of length cancel out and you're left with a dimensionless measure.

­You can think of a revolution as a measurement of an angle. One revolution is 360 degrees of a circle. Since the circumference of a circle is (2 x pi x radius), there are 2-pi radians in a revolution. To convert revolutions per minute to radians per second, you multiply RPM by (2-pi/60), which equals 0.10472 radians per second. This gives us the "per second" we need to calculate horsepower.

Let's put this all together. We need to get to horsepower, which is 550 foot-pounds per second, using torque (pound-feet) and engine speed (RPM). If we divide the 550 foot-pounds by the 0.10472 radians per second (engine speed), we get 550/0.10472, which equals 5,252.

So if you multiply torque (in pound-feet) by engine speed (in RPM) and divide the product by 5,252, RPM is converted to "radians per second" and you can get from torque to horsepower -- from "pound-feet" to "foot-pounds per second."
Posted By: fast68plymouth

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/18/17 08:14 PM

In laymens terms......

HP = (TQ/5252 x rpm)

At any rpm below 5252 the TQ is greater than HP, at any rpm above 5252 the HP is greater than TQ.

As for the question posed at the start of this thread......

I've seen so many dyno results that make no sense to me at all that I rarely bother guessing anymore.

With regards to this thread...... I see plenty of guesses...... But no cam data at all.

I would think there could easily be a 75hp swing between a .460 lift hyd cam vs a .650 lift solid roller cam.

Posted By: Cab_Burge

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 01:28 AM

Originally Posted By fast68plymouth


With regards to this thread...... I see plenty of guesses...... But no cam data at all.

I would think there could easily be a 75hp swing between a .460 lift hyd cam vs a .650 lift solid roller cam.


I'm sure your correct on the cam, it is a custom grind Comp Cams with lobe # 5965B on the intake lobes with .364 lobe lift and #5985B H on the exhaust lobes with the same lobe lift ground on 107 LSA and installed on a 104 ATDC intake lobe center.
It has 1.6 ratio Harland Sharp aluminum roller rocker arms also

UPDATE from today. We made several more pulls with no changes except for the oil and filter change and then tried one size smaller jet on all four corners, the AFR where showing fat(11.3 AFR) from 3500 RPM to 5000 RPM and then getting better to 12.3 AFR above that confused That change help a little bit also shruggy
Tried three more degrees of timing, 32 to 35 and that helped a tiny bit.
I decided to call it a day after that test due to the motor going into a street car with exhaust and air cleaner, we'll finish the tuning in the car with a wide ban up
The dyno printer wasn't working so the operator will E mail me copies tonight or in the morning so I have exact information as copied from the dyno information reports instead of relying on my old , feeble memory whistling
The weather changed from yesterday to today due to a low pressure front moving in, lower B.P., higher humidity with lower outside air temps. resulting in no big performance gains today whiney shruggy
Posted By: fast68plymouth

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 02:59 AM

Okay, so a XE285HL on a 107, with 1.6 rockers.

It seems everyone's dyno is different.......but, If I were dynoing it here.........and assuming it would rev high enough to reach its natural peak before any valvetrain unhappiness sets in.......and has at least 1-3/4" headers........I'd be looking for it to make real close to 500hp with ootb or very mildly reworked(more like "prepped") heads.
Posted By: Cab_Burge

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 05:59 AM

It was making peak HP at or under 5300 RPM, which didn't make since to me confused
I should have tried a bigger carb, maybe in the car later luck
The last pump gas 340 stroker motor I built, ( 9 second Phils Cuda W2 motor in 2002 or so) and dyno tested made 514 HP with a BG 850 CFM Speed Demon, 13 more HP with a 1050 Dominator on a adapter on the same intake shruggy
Bottom line is that I'm hoping this motor tuned well in the customers 1966 Dart GT will put a big old grin on his face at WOT devil luck
Posted By: pro451bee

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 06:24 AM

The Eddy heads have small ports.Causing the HP peak to be low.
Posted By: pro451bee

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 06:27 AM

Bigger carb wont help much .
Posted By: Dave Hall

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 11:06 AM

It's plenty! It'll be just fine! up
Posted By: fast68plymouth

Re: 340 pump gas stroker tests, guess results for tomorrow? - 10/19/17 05:44 PM

I've never really loved a fast rate hyd cam with higher rocker ratios.

If you had an air turbine on the motor to monitor air flow, there might be a clue there as to why the peak happened so early.

We dynoed a pump gas street 410 last year, rpm heads with mild clean up, small roller, 1 5/8-1 3/4 x 3 headers, victor, QF 850 carb........ Peak tq @ 4700, peak hp @ 5900, and only down 7hp from peak @6400.
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