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A 521 in Massachusetts


Crashtd420

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14 hours ago, Crashtd420 said:

I think 3rd....

Dyno sheet shows the peak hp at 67 mph ... 

 

I thought all HP are calculated by the increase in RPMs over time.... maybe not saying this right, but third will give a higher reading than 4th because it's a lower gear and why pulls are done in 4th. Differential gearing is also factored in.

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That sound brings back memories. When I worked for Rebello, I lived only about a mile away from the shop at their old location. Dave would do dyno work on Saturdays and I could hear the dyno from my house. I would sometimes wake up to the distant sound of L motors.

 

Sounds like a good little L motor.

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21 minutes ago, datzenmike said:

 

I thought all HP are calculated by the increase in RPMs over time.... 

That's a possibility .... the shop has a great reputation,  mostly high horsepower efi stuff.... so I hope he knows what's right.... I emailed just to see.... even if I am making less hp I'm still happy with how it went and how it performed...  plus I didnt destroy the motor so that's good..... 

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Ask the guy. Usually 4th or straight through to eliminate the transmission.

 

Just spent a hour trying to find out if there is a difference in 3rd or 4th gear dyno pulls. One idiot said dynos measure HP..... and torque is calculated from this... what a tool. To properly adjust the HP reading in 3rd I think the operator would need the 3rd gear ratio so using 4th or 1:1 keeps all pulls on the same page for comparison. The operator would also need the differential ratio. and RPMs of the engine. I read once that an unscrupulous operator will make a base run in 4th make adjustments or add parts then make a run in third which would inflate the numbers to make it look good. I wish I knew more about this. 

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Well I'm honestly doubting the numbers so I crunched some simple numbers....

 

If a stock L16 make 67 hp to the wheels

+ 10% 74 hp

+ 20% 80 hp

+ 30% 87 hp

+ 40% 95 hp.... I'm starting to doubt I've increased the hp by 40%.....

 

The dyno guy knows the dyno I broke my motor in on.... he says that one is over by 10% so that means my original hp number of 86 is more like 77.... 

To increase 18 hp from just tuning ?????

I think realistically if I'm putting down 80-84 hp thats 20-25% over stock that's pretty good..... 

If I'm actually putting down 95 then sweet if not so be it, motor still sounded sweet...

 

 

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 Doesn't matter what it reads unless you compare to another engine. It's a great tool for fine tuning small amounts of hp you can't feel driving. It points out what's working and what isn't under real load conditions. I don't suppose you made a base line pull before 'improvements" were made?

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There was a dyno run of L18 SSS duel SUs that had that claim of 77. Stock L16 was like 65-67 or so.So having a sss cam ,200cc more 1.5 in ports duel carb only added 10hp over stock. Having 85-110 of of a L motor is really doing pretty good . 75 hp or more with a  Weber DGV I would say is great also with a basic out out the stash distributor. If I could do it again I would have started out with L20s. This is just my opinion here .Im not a true expert on this but to get more hp out of a L motor is a work of art and a skill that most Ratsun people or not going to pay for when there or more torque motors like a KA or SRs out there cheap

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20 hours ago, Crashtd420 said:

Well I'm honestly doubting the numbers so I crunched some simple numbers....

 

If a stock L16 make 67 hp to the wheels

+ 10% 74 hp

+ 20% 80 hp

+ 30% 87 hp

+ 40% 95 hp.... I'm starting to doubt I've increased the hp by 40%.....

 

The dyno guy knows the dyno I broke my motor in on.... he says that one is over by 10% so that means my original hp number of 86 is more like 77.... 

To increase 18 hp from just tuning ?????

I think realistically if I'm putting down 80-84 hp thats 20-25% over stock that's pretty good..... 

If I'm actually putting down 95 then sweet if not so be it, motor still sounded sweet...

 

 

For sake of argument, when I was racing SCCA ITC in a 510, our engines were putting out 120-125hp on the engine dyno. A stock L16, according to common lore, made 96 hp. That's 30% right there.

 

Our ITC L16s were blueprinted stock engines with the 210 TK cylinder head, a U20 cam, recurved distributor, Weber DGV and Comp header with 2.5" exhaust.  You've got high compression, a big cam and a good intake. I think 40% gain with your setup is not implausible.

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19 hours ago, datzenmike said:

Engine dyno (or basically gross HP) is different from RWHP (or basically net HP).  My engine tag says 110 HP for an L20B yet other later tags say low 90s for exact same engine. 

I did say engine dyno. The numbers I gave were to illustrate the percent gained.

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Well stroffgren I hope your right... I like the idea that I actually achieved 95hp.....

 

This is the response from the dyno shop...

"Yes, the rule of thumb is you would ideally like to use the 1:1 gear.  However, we also don’t want to see the pull take more than 2 seconds per 1000 RPM of wide open throttle.  I tried a short 4th gear pull and with  the level of HP you are at, the 4th gear pull is way to slow and puts too much stress on the motor.  Generally, this also generates a ton of heat and the engine loses power over the 3rd gear pull anyway.  So I think what you have is the most accurate results we can get."

 

And I'll leave that whole dyno conversation at that..... 

 

 

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I say bullshit to them. Who the hell hasn't held the throttle full open for more than 12 seconds. It's NEVER going to stress the engine. If you are merely looking to measure peak HP start the pull at 4K then. Now I suspect that they are inflating the output by using 3rd gear. 

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