Dyno overlay

The dyno operator just sent me the overlay graph from last week. Upper line is new motor, lower dash line is old motor.

that lays over pretty good on top.i would think that maybe with the smaller cu engine and sr71 heads,it would continue to rise past that peak.even the p51s had a flat curve on top.
what restriction would cause that? carb,timming,fuel supply,valve springs?

These heads have the 1.64 blue stripe springs with titanium retainers installed. Randy mentioned in the other thread that using 1/16" rings with the 4.50" stroke crank can cause ring flutter as a possible problem around 7k rpm. Too much piston speed for the rings to stay sealed up. These pistons are 1/16" rings and no gas ports.

glenevans wrote:These heads have the 1.64 blue stripe springs with titanium retainers installed. Randy mentioned in the other thread that using 1/16" rings with the 4.50" stroke crank can cause ring flutter as a possible problem around 7k rpm. Too much piston speed for the rings to stay sealed up. These pistons are 1/16" rings and no gas ports.

That's not what it is. It's the intake manifold keeping it from running higher.

did yoy run an o2 sensor on the dyno for afr? so that engine is maxing out the mafia intake?would porting help or just needs a bigger intake.it does have 2 spacers on it.kaase made 938 on his 521 with less duration on cam.
never the less its a neat engine and car for sure!

We did run o2 sensors in headers. 114 BLP jet which corresponds to 93 Holley jet. Mafia manifold is lightly ported/smoothed, was running a 3/4" open spacer under the Jomar tapered spacer. 1150 Holley with billet boosters and metering blocks, .020 I and .022 E lash (Hot). Best overall power was 24* to 26* timing advance. My wife is very jealous of the car, had it since '82, her since '87....ha ha

So what is the LSA, and what and what ICL was the cam installed at?

Kaase was at a 116ICL to get that 1224HP at 8 grand on the 598. It's an apples and oranges comparison but I was just curious.

Is that block still 2 bolt?

I hate to link FacistBook but, it's the only place I see Charlie's 611/SR-71 intake dyno comparison.

Anyway the Air Boss was worth 15HP, over the Mafia, and about 65HP over the Victor and AFR that was tested. All with a 1050 Dominator and all in at 6,900 Rpm.

https://www.facebook.com/photo/?fbid=2637467229604023&set=pcb.2637476736269739

With the 2.3" Carburetor/Air Boss and vacuum pump, plus carburetor spacers, it peeked at 7,000 Rpm and picked up 72.3HP, to 1,137.8HP from the original test of 1065.5HP.

Size Comparison of the AirBoss and a Mafia.

https://www.facebook.com/photo.php?fbid=10216700567959421&set=p.10216700567959421&type=3

With Vacuum pump and 2.3" Dominator Dyno Sheet.

https://www.facebook.com/photo.php?fbid=2479107692372579&set=p.2479107692372579&type=3

And Cam Spec.'s.

https://www.facebook.com/photo.php?fbid=2479101825706499&set=p.2479101825706499&type=3


This all was in 2019 and likely was one of the first SR-71 combo's tested?

I thought this would be a good place for the info, as there is not a lot of it in here (SR-71 Builds), or I missed it.

I believe cam is 113 LSA, have it advanced 2*. Yes, 2 bolt block that is bored .060 over.

glenevans wrote:These heads have the 1.64 blue stripe springs with titanium retainers installed. Randy mentioned in the other thread that using 1/16" rings with the 4.50" stroke crank can cause ring flutter as a possible problem around 7k rpm. Too much piston speed for the rings to stay sealed up. These pistons are 1/16" rings and no gas ports.

What did you change on the P-51 short block besides the cam? What size headers did you run on it?

I went from 1/16th rings not gas ported to .043" and gas ported but didnt see much of a difference. No dyno work here in either case. Ring flutter is no joke but I wasn't in that realm at 7,000 rpm. The main issue that I had was extremely lean corner holes. I modified the Mafia intake by blowing the plenum out at both ends almost 2 inches. The plugs look even now so all is happy. If I want more power I'm going to need a bigger cam. I like Glenns power curve comparison where the SR's are higher past 5300 rpm. I hope that 2 bolt block doesn't walk the mains badly.

Previous dyno used only 2" headers. This time he used 2 3/8" merge header according to the sheet info. I do have a 4 bolt SCJ block ('72 police interceptor) to use after I finish getting it welded. Last time rods broke, it took out two pieces of oil pan rail. That's why this current motor has full groove bearings. But I think the solid windage tray fixed most of the oil control problem, was using a screen type tray before. Overall very happy with results. Now just need all this freakin snow to go away!

^ What I was getting at Glen is if P-51 block had the thinner rings and or gas ported pistons, since you said it pulled to 7,200? It doesn't look like your air fuel ratio changed much, on the dip between 6,300 and 6,700Rpm. It actually got a little bit fatter. Not sure what that is about but, I doubt it's springs or timing. You are kind of living on the edge now with that block so it's making enough.

2019 to 2023 is a long time between dyno pulls, I am wondering if it has been recalibrated since then. I have also seen a lot of 545-557 dyno sheets with different heads, including P-51's, and don't recall many pulling to 7,200Rpm peak either. Even most of the high compression, biggish roller cam 460's are below 7,000 peak HP.

Get her to the Track and post up some Times and MPH's, that where it counts.

glenevans wrote:Previous dyno used only 2" headers. This time he used 2 3/8" merge header according to the sheet info. I do have a 4 bolt SCJ block ('72 police interceptor) to use after I finish getting it welded. Last time rods broke, it took out two pieces of oil pan rail. That's why this current motor has full groove bearings. But I think the solid windage tray fixed most of the oil control problem, was using a screen type tray before. Overall very happy with results. Now just need all this freakin snow to go away!

Too big and too little. 2-1/4" would be best imo.

Sorry for confusion, I only meant he pulled it to 7200 on 2019 dyno test. It was pretty much "flatlined" from 6500 to 7200, only gained about 6 or 7 hp total. Old shortblock was exact same piston/rings as current (1/16 no gas port) Good news is, the header pipe kit we now have is the 2.25" size. I have also noticed most all these dyno tests end around 7000 rpm without different intake options.