as the title suggests, what combinations do/have you run on the street using pump 93 ?

493 stroker
Eddy RPM heads cut to 76cc's and port matched
Deck height .015"
Scott Brown STF cam 259/266 @ .050 .637/.623 lift with 1.6 roller rockers
Victor intake with 1050AN Quick Fuel
2" CPPA headers
Timing all out by 2K
11.8:1 COMPRESSION
3926 LB B body 4 speed tranny with Centerforce clutch

Pump gas 93 octane

How high of a compression ratio are you wanting to know about?
I shoot for 10.5 or less with aluminum heads on customers motors, 9.5 or less with iron heads
I have a 505 C.I. 400 block that has a little over 11.3 to 1 compression ration due to the 440-1 heads having little tiny 50 CC combustion chambers
I haven't ran that motor in a car yet but I'm hoping the camshaft, 262@.050 intake and 263 @.050 on the exhaust lobes ground on a 105 LSA will drive okay with no pinging
My street pump gas stroker motor in my Duster started off with a set of mildly ported big valve 906 iron heads with 9.25 to1 compression that combination made my 3450 lb Duster run 10.69 at 124.+ MPH with a low deck six pack set up.
I switch the heads to a set of CNC ported Eddy RPM with the same size combustion chambers that had the same compression ratio, those heads made the car pickup so it ran 10.49 at 126 MPH
The next winter I swap the crankshaft from a 4.25 stroke to a 4.300 stroke to raise the compression ratio up to 10.29 to 1 and that picked the car up to run 10.30 at 127. MPH.
The last parts changed was another set of heads, Indy SR M.W. ports along with a Indy 400-1 intake and a 1050 CFM Holley Dominator carb, that ended with a best ET of 9.993 at 134.6 MPH

4.375 x 4.375
10.85 compression
Ported TrickFlow PP 270's
.714 tight lash solid roller (262@.050Int/268@.050Exh)
.035 quench
20 degrees initial - 34 total in by 2800. Advance set to not start coming in until ~1600rpm (probably switching to locked distributor this summer)
180 stat
3800 stall
4.30 gear
3800 lb Coronet

I run just regular 93 pump gas and have had no issues with detonation so far. No signs of it on any plugs, and nothing that was audible. I did sweat the details and made sure I knocked the sharp edges off anything in the combustion area and also polished the chambers to fight carbon buildup. I am a firm believer in a tight quench motor. My last build ran .027 piston to head clearance. On teardown I could see the slightest hint of a witness mark on the intake side of a few pistons so I opened it up a little on my next build. I didn't see any hint of collapsing the rind lands so I figure I was ok but still wanted a little insurance.

I hope this helps.

That sounds like a nice combo! Any time slips that you care to share?

Define "high", please.

68LAR - 11.8? I thought you'd posted that you were about a full point lower (10.8?), but my memory's turning into putty.

I had a 12:1 484 cube injected Hemi U ran on the street for years....That was a blast

Now I have an 11.5:1 605 Hemi.....More fun

And for Wedge motors I raced a 512/440 at 10.7:1 on pump gas that went 9.70 at over 138mph

This year we built a 512/400 at 13:1 and we will see if we can get it to run crap 93 with octane booster....

Me thinks you be messin with faith with that combination
Maybe try E85 instead
I'll have another post soon about a 518 C.I. 400 block I dyno tested this week on E85 after I figure out what part went south in the ignition system on the dyno yesterday
Hopefully I'll get it figure out this weekend

sorry. should have said above 10.0. just going through some mental exercises [at my age ? ] and thought, or had, one of those "what if" moments.
anyone else care to chime in ?
thanks to those who responded so far !

We are starting on race fuel and going from there. Its mild enough to street it.....But we want to go faster than 9.70 on the track.

10.8 cr 452 RB with Stage VI heads, Victor intake, and 266 at .050 x .600 sft cam pushed my Challenger into mid-to-high 10s on 93 E10.

I'd expect that I could equal, or improve, the results today for far less hassle using TF 240 heads & intake.

Nope, I don't remember posting that? But like you, my memory is also turning to putty. If I did post that, I was wrong and probably had a case of fat fingers and hit the wrong key?

Unfortunately not yet. With what the heads flow (382@750 and really nice mid-lift numbers to match), I am hoping for anything sub 10 seconds. On paper, it should make it there but real life seldoms meets those predictions. Based on the prior motor, I am thinking it will likely be somewhere in the 10.20's. So far it is the best compromise motor I've built. Starts right up all the time, idles off within 40 or 50 seconds of running in 50 degree temps and isn't a pain to drive on the street or highway (other than the 4.30's being a little big but a tall tire and overdrive help that). It makes 2.5 hour journeys without flinching and still gets 11+ to the gallon on the highway.

Much of the conversation depends on what you really want from your "High Compression NA Street Combo".

For instance, some people want to drive it hard on the street, and race it at the track with out ever adding race gas at all.
Others, don't mind having an engine that runs good on the street with pump gas, but when they get to the track, and tune for best ET, they add race gas.

Still others have "Street engines" that have to be de-tuned and driven like an eggshell is under the pedal to avoid detonation on pump gas! I've had one of those and after awhile it just sucks the soul right out of you and makes the street experience unbearable! In combos where we've missed just a little, I will add race gas to every tank on the street because I refuse to not be able to enjoy the drive. My brothers, however, are cheap, so even many of their bracket cars were pump gas combinations because they refused to buy race gas.

The 428 small block in my Valiant is 11.0 to 1. 4.125 stroke by 4.07 bore. The flat tappet cam is 269/275 @ .050 , .600 lift, on a 111 c/l, installed at 107. Made 615hp @6700 on dyno.
We don't have access to 93 most of the time, but I've ran it hard on 91, several times on Drag Week I've resorted to 89, and occasionally 87 with nary a whimper. Love this engine on the street!

The 580 Mega Block in Dale's Gremlin is 10.8 to 1. Nitrous spec cam is huge, 282/296 @ .050, 750/730 lift, 114 c/l. 352 cc Indy -1s, Tunnel Ram with twin Dominators. Runs around on pump gas with no issues, has been 9.47-144 NA with Nitrous gearing and bad converter.

One of the problems we've ran into is converting filled block race engines to street use, oil temperature control is tough, and as such they tend to be detonation prone in street use, even though the compression and cam seems like it should work.

11 to 1 iron magnum heads, 231@.050 110 LSA .575 lift single pattern cam. Full ported factory magnum heads 2.02 stainless valves mirror polished to keep from absorbing heat as much as possible 410 SB I pulled all the tricks I could think of to make it work, mopar air gap single plane intake, routed fuel lines outside frame away from ex heat, ceramic coated long tube headers, CAI picking up air in front of radiator, EFI, I cut all the webbing out of the accessories bracket to keep air flowing through intake, heat shield under intake to keep hot oil off intake, 160 t-stat, big diesel fan to keep lots of cooler air under hood, throttle response is insane and pulls hard from idle to 6000RPM.

Race/93 mix at the track, pull some timing and run 93 on the street😀

That's kinda the plan....Should make north of 700hp this year.

Well mine is not what I call high comp as its 10.6 comp. I run a 440/493 combo that's a .030 over 440 with the 4.15 crank. I run on 92 pump since we have it in my area but it should run fine on 91 or less even as it has no detonation at all with 36 total timing. Here is the basics:


440 block with 4.15 crank

440Source stroker kit with D-dish pistons for 10.6 comp and .046 quench

The basic Indy EZ heads with some work from Dwayne Porter

Dwayne Porter solid flat tappet cam that's 264 & 270 @ .050 and .585 & .592 lift with a 110 LSA on a 106 ICL

Indy dual plane intake and 850 Holley DP

Mallory dist with MP orange ECU and 36 total timing

TTI 2" headers and the full 3" exh out the rear of the car with Ultra-Flow mufflers

Hughes roller tip rockers and Manton pushrods

Its in my 63 Sport Fury running a 727 with a 9.5 Dynamic converter and 4.30 gears using 30 x 9 Hoosier tires. I race my car just as I drive it on the street which is through the full exh on 92 pump. I don't change anything at the track as I built mine to race and drive without making any changes and I usually drive it to the track. Actually its never had race gas in it and I have never uncapped it. So far its run 10.70's . Ron

Wouldn't cylinder pressure be more appropriate?

Big cams bleed cylinder pressure requiring more comp do they not?

Hysteric

what would be a "minimum" overlap, or duration at 50, when approaching 11 : 1 static compression ?
and to add to the mix, how does fuel injection [throttle body or individual injectors] and carbs compare to each other in this situation ?

I run non-oxygenated 93 octane pump gas. Combo is a 400 based 452” 3.75 stroke at 10.65:1. Heads are 84cc Source Stealths that have been milled & cc’d at 82cc. Flat-top Iconn pistons are at zero-deck. Cam is a flat-tappet solid, 252* (.050) & .573 lift. (Currently at .610 lift with 1.6 rockers.), on a 109* c/l. I’ve been beating on this low-budget home-built combo for 9 years now, and still finding more in it. A new best was just found this past weekend.

It's not that simple: chamber design, piston top design, quench height, camshaft seat duration, LSA... not even all of the variables that can factor into this.

Also, some people say the overlap influences cranking pressure, I've always understood it to be a result of the intake valve closing point. A lot of overlap does impact the ability of the engine to have more complete combustion at lower RPMs That's not cylinder pressure; it's dilution of the air/fuel mixture with residual exhaust gasses.

And, there's been a running debate (about which I've presented my position in the past) of whether the engine build should target cylinder pressure based upon using a "higher" CR and crutching it with a longer-than-normal-duration cam, or targeting a more "typical" CR for the fuel to be used and spec'ing the cam to be aligned with that CR.

I've been through that last topic enough that it's now included in my no-no discussion categories, along with politics, religion, and choice of engine oil.

400 based 496, pocket ported Ed heads, 243@.050 mechanical flat tappet cam, 10.2 CR. EFI. Zero deck and .042 quench with "D" dish piston.

Truly "street driven" including summer trip from IL to CA and back in 9 days. Desert temps at sea level to freezing over 7500'. I ran the Silver State route backwards. Did fine.

Also run hard for extended laps on a road course.

With this combo, I would not want more compression for extended street or extended road course driving.

Been running the Charger on 100 Unlead with 12.4:1 compression.
No that I have the EFI, I may try 92-93 octane. With the EFI it is easy to load up different tunes.
I need to finish the wiring on the convertible, using FAST XFI 2.0 with flex fuel sensor.

There is a guy on forabodies only that has a 360 with aluminum heads with I think 11.3ish compression and he claims it has 1000s of miles on 87 octane,,, he posts quite a bit about calculating DCR along with how gear ratios should be considered etc.

Hemis are more tolerant to detonation than a wedge supposedly. My hemi is 11:1 and runs great on pump 93 (9.50s at 140 mph). Never tried any less octane. It slows down a tenth and about 1.5 mph on 112 race fuel, but it goes a whole lot faster when I turn the nitrous on.

I've been running an 11.2:1 440/496 Wedge for over 3000 street miles. I have a basic 440 Source package with Stealth CNC ported heads. The cam is a Comp Cams .575 street roller. I run it on 92 or 93 where available. At the track I'll mix in some 112 octane from the race car just to be safe. No pinging at all. This is pretty much a street car with track visits a couple of times per year. Best ET so far is 11.04 @ 122...through the 3" exhaust, and with tail pipes. Heading to the track in early June for a rental, but my son will be driving it for the first time. He's 100lbs lighter than me. Hoping for the elusive 10 second slip.