512 low deck on the dyno

Made a little over 700 hp with a 1050 carb now we're switching over to a Holley Terminator throttle body. Should have it running early next week, just waiting for a cable from Holley to show up. Engine is a low deck 512 with TF270 heads and a 264/268 solid roller. Intake is Indy 400-3 unported so that is costing some power. Very similar build to the low deck 470 that I was running a few years back but down on power from that engine. I pushed my low deck 470 up past 750 hp on the same dyno using the same cam, heads and headers but I had a ported intake, a really good oil pan and a belt drive.

Any more details on the combo Andy?

Pump gas street/strip deal. What else would you want to know?

Compression, rockers, pushrods,rings, pistons, head flow, valve sizes, cam type and lift, did I miss anything?😁

Stop tempting me to EFI the dart. I already have the O2's, fuel system....and my 1050AN doesn't like my 451 unless the n20 is activated.

Is this a 4.25" stroke/6.535" rod/2.200" journal combo?

Heads are out of the box,

A Sniper 4500 would bolt on your combo fairly easily. I think it is a 440Source rotating assembly but I'm not positive. Parts have been hard to come by recently so the engine shop uses what they can find.

Made a few pulls today and ended up with 730 hp peak at 6200 rpm. Not bad for a pump gas bracket engine made from "out of the box" parts. With the power band that low it should last a long time for the guy. Shift it at 6500 and it should live for years.

Sounds like it gained 30 hp with the injection system.
Those OTB TF270 heads are pretty good.

Is the low rpm due to the conservative (low duration) cam?
Goes with the CR.

Very nice, thanks for sharing. Would like to know CR and more cam/lifter/rocker info, thanks.

Maybe, hard to say what is causing the peak to be where it is. I've chased it around a bit with the 270 heads on 500 inch short blocks and my guess is that it is inherent in the design. A professionally ported intake can move the peak up a bit but more duration or more lift doesn't seem to move the peak up very much. Dwayne might have some thoughts on the subject but I don't know if he has actually made the modifications and successfully moved the peak RPM up with these heads.

I tested a lot of cam profiles and bunch of rocker arm ratios with these heads. What I found is that they only want so much. A bigger cam doesn't automatically move the peak RPM up nor does a bigger cam always make more peak power. 264/268 might seem like a small cam but if the cam is much bigger the power drops off. In my pump gas 470 a cam with 270 duration made less power than the 264/268 so it was pretty touchy about how much duration it wanted. This equation would change with more compression but not as much as you think. I have a customer with a high compression 505 running TF270 heads and with a 280 duration cam it makes 750 hp in the 6500 rpm range. I think his cam is too big but that is what his engine builder told him to go with.

Some people might want more power at a higher RPM but I think a lot of people would be happy to be able to make 700 hp with OOTB parts. Sure is a lot better situation than it used to be. I think a person could make 800 hp with the TF270 heads but my guess is that the valve job would need to be changed. I think the TF valve job is the key to 700 hp and the barrier to 800 hp but I don't know that for a fact.

CR is around 10:1 and the cam is the same Comp 264/268 that I've used in the last few builds. I don't know what the rocker arm ratio is and it doesn't really matter anyway. 1.5, 1.6 or 1.7 will all make the same power in an engine like this. Higher ratios just work the springs harder.

That 470 makes real nice power for a street deal. Accually it makes more than my 12.5:1 511 with max wedge heads and no junk parts on this motor. I figure about 630hp according to the moroso slide rule and using a 270@50 cam. Also, that 470 according to moroso slide rule , would put my combo into the 9.50's at 140+ mph.

Imo, the 700-750hp range is the sweet spot for the TF270.

To get beyond that, I think it’s a situation where the port area is trumping the flow numbers.

The interesting test would be a TF270/SRcnc295/440-1cnc325 shootout.
The caveat is that the Indy heads would really need to be gone thru to get the valve job situation comparable between all the heads.

The intake flow at .700 lift would be pretty close between the 3, with the intake port volume getting bigger as you moved into the Indy heads, along with the exhaust flow and exhaust port size.

I think on something like a 540, and targeting 800+hp, you’d find it’s easier to get there with the bigger Indy heads.

For sure, the TF heads would still win the “bang for the buck” award.

I'm pretty sure you're correct on all those points. If a guy comes into the shop and asks for 700+ hp for a bracket car then I'll usually recommend a 505 with 270 heads and a modest solid roller. It is a fairly easy combo to build and they always hit the number, even with OOTB parts. If a customer said they needed 800 hp then I'd recommend a bigger head, maybe a Big EZ or a -1 depending on what the header situation was. The problem of course with Indy parts is the extra labor required to finish them before use. That adds some money to the bill so the customer has to understand that the price goes up.

Looking at it another way, if you had a typical high CR bracket race 540 with some Indy heads on it, and it was making solidly over 800hp......... and you swapped the heads for the TF270’s......... I would expect there to be a noticeable hit to the HP, along with the upper end of the curve falling off quicker.

But....... that’s purely speculation on my part.

I was going to post/ask that the lower RPM peak of the TF270 on the 511ish CID engine may be due to port volume.
But Dwayne pretty much summed it up.
For a 500-540 engine, 700-750 hp at a nice low rpm goes to the TF270.
For more hp, more port volume would help those size engines. Expecting the peak RPM to go up with it

Too bad they are basically out-of-stock everywhere.

I would expect the same thing. Putting a TF270 head on a 800 hp engine would most likely turn it into a 750 hp engine.
I think the TF head is perfect for a stock block bracket guy. If you have a stock block then you don't really want an 800 hp head since you'll crack the block. So a super nice CNC head that delivers 700 to 750 hp right out of the box is a perfect solution. Guys who have stepped up to aftermarket blocks should also step up to a head with more capability since there is no reason to limit themselves to 750 hp.
The interesting thing that I don't fully understand is that TF heads require a different fuel curve in the mid-range than other heads. I saw that yesterday on the dyno and I've seen it several times before. At WOT they behave normal but high vacuum cruise conditions the "normal" fuel map is way off with these heads. The ECU goes crazy trying to compensate when we're warming the engine up on the dyno but then it runs smooth as silk during the WOT pulls. I've seen that every time I run Trick Flow heads with EFI. Pretty sure it is the valve job with the high flow at low lifts.

Tough trying to get someone to let you experiment with their new heads....... but it would be interesting to see how the EFI responded to a slightly larger throat diameter and 50* seats.

If it was in fact a “street/strip” vehicle, I’d probably sacrifice a few peak ponies for some better manners when the exhaust is closed up by spreading the lobes out a bit.

Well-put!

I just reread the entire post WITH the updated dyno. This sure seems to be a well-done combo! IIRC i looked-up that cam profile and it is PRETTY FAST RATE/bigger than the numbers would indicate at a glance. Which also speaks to the varied theories as to why it makes power and where at. At some point in RPM valve control will be an issue. Generally comparing this and an engine with 40 Cu In less AND what general camshafts a certain head would want, i would think we should add the consideration of static compression.

As I recall, when that cam was first used....... it was in the 470 with the 240 heads. And there was a spring change done on the heads as well, to K-motion K-950’s, which have a higher rate and a higher lift capacity...... to facilitate the planned rocker ratio test.

At .700 lift, the K-950’s would have almost 100lbs more force than the springs that come on the TF heads.

i guess i am this guy . Sometimes you need to limit the car for safety . My car is legal to 10.00 , cage restricted , so no need for the extra HP . I have no desire to go faster as that entails cage upgrades , SFI recert/replacement , going to a delay box , might as well go a roller cam , licence upgrade , and really i would need a tow car and trailer .
I split a stock block @ 650ish , now have a World iron block .




Tex

After seeing Dwayne's 4500 flanged street dominater intake in my GTS thread this could work. Is the terminator any taller than a normal Holley?

This has been an informative thread thanks for posting up on your results.

Throttle bodies are typically shorter than carbs but the measurements can vary. If you go with an air only throttle body (port injection) then the throttle body can be very low profile. Wilson make a 2400 cfm Dominator flange throttle body that is fairly low profile. Spendy of course. https://www.wilsonmanifolds.com/col...ts/4500-throttle-body-2-55-bore-2400-cfm

I split a stock block @ 650ish , now have a World iron block
Tex .....kind of curios was this a tall deck or a short deck block and what weight?......Thaxs.

Racerx . RB block . Just under 3700lbs . It was stuck in the 10.50s with CNC source heads , started showing a smidgen of moisture in oil then blew a little oil out but ran great . Swapped TF270s on thinking heads but nope . Went faster still broken .
I imagine most after breaking a block would if possible then step up the block to avoid a catastrophic failure and possible vehicle damage . That was my thinking . Still have my stock stroke 440 less worrid about that .

Tex

Thanks