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Redheaded Stepchild, High Performance TPI project. Dart 165 vs. Chevelle Bowtie through TPI

Charles Servedio cylinder head porting & flowbench

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We test the Dart 165 with 1.94" valves against my Chevelle Bowties with 2.055" valves through the whole tpi manifold. interesting results.
This test has the wrong size valve 2.02" textured on a 1.94" seat in the Dart165 head so take this test with a grain of salt! This makes the head flow better than 1.94" valve. This was a mistake but maybe something can still be learned from this test. Thanks

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5 сен 2024

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Комментарии : 21

@robmartin5382 2 месяца назад

Velocity I would think. The Bowtie heads are good pieces. Good comparison IMO just to look at the port roof fiasco.

@dondotterer24 2 месяца назад

Awesome job Charlie! I'm thinking that with the TPI manifold stay with the 1.94.

@servediocylinderheads 2 месяца назад

Too late! Ha!

@jsomething2 2 месяца назад

I'm curious if you have any older videos on a deep dive into the old twisted wedge trick flows for sbc. always seemed interesting to me as someone that knows nothing about head porting and flow lol. enjoying the tpi stuff. Hopefully he builds the motor and we get to see what all the hard work provids.

@servediocylinderheads 2 месяца назад

Never did a twisted wedge. I don't like the valve train issues, so I never did any. Thanks

@servediocylinderheads 2 месяца назад

He now works at a shop with a dyno and 383 is planned so stay tuned!

@jsomething2 2 месяца назад

@@servediocylinderheads oh, I had a set years ago when they first came out and put lots of miles on them, didn't realize they had valve issues. I just Googled and I see. I think mine are still laying around my shed somewhere haha. oh well, I was curious what you thought of them with tpi, since that's how I ran them years ago and they seemed to work pretty well for their time.

@mikkokuorttinen3113 2 месяца назад

Hi Charles! Perhaps unrelated to this particular video, but the one before with the oversized valve. I wonder how much of could we reduce the valve dish diameter (by grinding) to keep it still functional (= not leaking the pressure due to too narrow sealing surface)? In theory, this should improve the flow into the chamber if it's shrouded with loosing any compression.

@servediocylinderheads 2 месяца назад

You would think but no way to know without testing. Thanks

@mikkokuorttinen3113 2 месяца назад

@@servediocylinderheads Perhaps the technical term would be under cutting the valve dish?

@andrewburlock2653 2 месяца назад

Hi Charlie. Isn't there situations where an engine can make more power even though the work done on the flowbench showed little gains. I'm just guessing here but I think with a 383 the larger valve may work better even if it doesn't show much gain. Why do you think your bowties don't flow that well down low? Shouldn't the larger port and valve flow better? Not criticizing just learning. Andrew

@servediocylinderheads 2 месяца назад

Good questions. The Dart is quite efficient even with the wrong size valve. Thanks

@stevecowan1362 2 месяца назад

Velocity and cfm go hand in hand,the test pressure is the same but the bigger head has more cross sectional area from the flange to the throat/ valve diameter/ area. Velocity is down on the bigger head so the cfm will be down. Just remember when you make everything bigger as in ports,manifolds, carbs,cams etc it moves the average and peak power higher in the rpm band. You can not bandaid a to big of a port with a small manifold. It does not and will not work.

@jamiebrown4322 2 месяца назад

@@stevecowan1362 bingo! Pressure gradients with area change get all messed up entering the bigger head port from manifold. Say hello to excessive turbulence.

@roberthollinshead2325 2 месяца назад

The seat angles and throat percentage differences account for the low lift flow difference I would think.

@roberthollinshead2325 2 месяца назад

What lift cam is going to be run-I think that determines what valve job and throat percentage is used. A bigger valve should kick butt over a smaller valve everywhere If the seat shape and throat percentage is the same-at least until chamber shrouding becomes an issue. At lifts up to .500 the throat size and valve job angles are probably most important. The Darts have a nice seat design from the factory. If duplicated for a larger valve it should do much better if the port can feed it and shrouding isn't an issue. Forget about flows at .600 and .700 if this is going to be a .550 lift motor.

@servediocylinderheads 2 месяца назад

Nah, I' ll pass! Thanks

@stevecowan1362 2 месяца назад

Valve size is a ratio of the bore,the valve job is governed by the chamber,bowl and short turn height and shape. As I have mentioned before if you are small on area further up from the throat putting a bigger valve won't help power much. An example is a 1.94" intake valve with a 89% throat has a area of 2.27" includes taking out stem diameter of 0.09" for a 11/32" stem. At no point is there area further up the port or manifold runner with a bigger area so the sonic choke won't be the throat/ valve area. Also with cam lift is a by- product of cam lobe duration through design. The more duration equals more lobe lift then you can add rocker ratio to speed up valve motion. When I port cylinder heads I make sure air is stable at the highest depression 0.100" - 0.150" above max valve lift. I don't worry about flowing to 1.000" of lift but that's just me.

@servediocylinderheads 2 месяца назад

@@stevecowan1362 These are good practices. Thanks