Cam Suggested Compression Ratios..

[Skylor]

Dodge,

They still do sell race fuel here in cental MO at the pumps.

It's called E85!

pdq67

We got Blue Turbo 110 leaded for $7.50 a gallon--my Dodge Freak account got zap, I'm trying to get it back...I knew I forgot to update all my emails

[BlackoutSteve]

LSA could have an effect in that it changes ICL which changes IVC. That is why I ask for seat-to-seat IVC. If I have the same lobes changed from a 106 LSA to a 113 LSA and advance the 113 LSA cam 7 degrees my ICL and IVC are the same as the 106 LSA installed at 106 ICL and so is my DCR>

Stan

COMPGAUG.GIF

So two cams in identical engines, both with the same IVC point but with differing LSAs always have the same DCR?

[af2]

LSA could have an effect in that it changes ICL which changes IVC. That is why I ask for seat-to-seat IVC. If I have the same lobes changed from a 106 LSA to a 113 LSA and advance the 113 LSA cam 7 degrees my ICL and IVC are the same as the 106 LSA installed at 106 ICL and so is my DCR>

Stan

COMPGAUG.GIF

So two cams in identical engines, both with the same IVC point but with differing LSAs always have the same DCR?

NO it is the starting point!!!

[BlackoutSteve]

..starting point..

[af2]

..starting point..

On close..... Where does the intake close????

[Stan Weiss]

LSA could have an effect in that it changes ICL which changes IVC. That is why I ask for seat-to-seat IVC. If I have the same lobes changed from a 106 LSA to a 113 LSA and advance the 113 LSA cam 7 degrees my ICL and IVC are the same as the 106 LSA installed at 106 ICL and so is my DCR>

Stan

COMPGAUG.GIF

So two cams in identical engines, both with the same IVC point but with differing LSAs always have the same DCR?

These are the inputs I use to -- Calculate DCR -- Compression Ratio, Bore, Stroke, Rod Length, Intake Valve Closing Cam Timing, and Wrist Pin Offset.

Stan

PS -- I use these -- Estimate the Compression Gauge reading (PSIG) from the Compression Ratio, Bore, Stroke, Rod Length, Intake Valve Closing Cam Timing, Barometric Pressure, Temperature, Humidity, and Wrist Pin Offset.

[pdq67]

Our local E85 is right at 104 to 105 octane depending on the time of the year. And it is cheaper than regular unleaded so go from there..

I want to say now that our gas is up to $3.69/gallon, it is probably $3.45 to $3.50/gallon.

Guy's say that E85 at 85 percent is good to go up to 17 to 1 CR in a dedicated boosted engine........

pdq67

[BlackoutSteve]

have a cam in mind for you. It is a UD Harold Cam. (Ultradyne) UD Harold is the right guy to talk to
about this cam and your motor. It is not a custom cam. It is a off the shelf cam. But Harold may want to adjust it.
He is a cam expert and this is his cam. 11.12:1cr is plenty compression for this specific camshaft.

It took a little while but I did get a response to my cam enquiry from Ultradyne.

With 11:1c/r..
@.020" = 289/295°
@.050" = 259/265°
lift = .731"/.731"
lobe sep = 108°

With 12:1c/r..
.020 = 291/297°
.050 = 261/267°
lift = .731/.731
lobe sep = 108°
both cams lash @ .020/.022"

Crane 138801 that I have "in hand"..
(no duration info @.020")
@.050"=262/272°
lift = .714"/.714"
lobe sep = 106°

I would like to know where the Crane cam is too small and how it is the wrong cam as Ultradyne's recomendation is similar (slightly smaller) and only has a tad more lift (+0.017"). Lobe seps are about the same with the Crane's 106°being better with this heavy car, I dare say.

I asked for a 12:1 recomendation to kind of compare apples with the existing Crane, but I have decided not to go 12:1 with this rebuild, and to remove the water injection.
I'm not 100% sure what the end c/r will be but it will be around 11:1. It just depends on what pistons I end up using -hopefully my existing custom Ross'.
DCR with 11.15:1 is around 8.5 using the Crane cam. I assume that 8.5 will be OK on pump fuel, or is 8.5 boarderline? Should I drop it a little more to be safe?

[sleeper]

Hi blackout Steve.
I am from Australia and have been running a 454 chev in my street car.
It has 11.3:1 compression Brodix aluminium heads, and I am running the crane f260
solid flat tappet cam.
Specs are.
@.050 Intake 260 Exhaust 268
@.020 Intake 296 Exhaust 304
LSA 108... Intake valve closes at 55degrees abdc @ .050
and 76 degrees abdc @.020.
I have been using pump gas, 98 octane, and have not had too many issues
with detonation. The only time I have heard some is on very hot days around 90 degrees,
with the engine temperature around 185 degrees going W.O.T. in top gear and that depends
on the fuel quality as it does vary a lot.
It sounds like my combo is similar to yours, I am running turbo 400, 3.55 diff and when
accelerating through the gears there is no audible signs of detonation, also no signs on
the plugs which I check regularly. I think 11:1 would work with the cams you have listed
using pump fuel with a good quench setup. I don't think my combo would tolerate any
more compression with the cam I am using with the intake closing events that it has,
and would probably be better at 11:1 comp, but I have had no problems......Mike.

[F-BIRD'88]

I had two Lunati UD HAROLD (ultradyne) cams picked for you.
For 11:1cr and the AFR heads or reworked edelbrocks and a TH350 transmission and 5000+ stall.
They are both .710" lift
502A8LUN N/A296/308 265/276.710"/.710"109/103.030"/.030

502B1LUN N/A304/310 270/276.710"/.710"110/104.030"/.030

NOTE * (in the Bullet and the Lunati cam lobe library this 304-310 cam is 268-274 @.050" .711" lift) .030" lash

These are UD Harold "Ultradyne" cam grinds. made by Lunati
You can get them from Bullet and direct from UD Harold too.

These cams may first appear much bigger to you cause the .050" duration is
bigger, but look at the valve lash difference. .020' VS .030"
The actual net valve duration at the valve will be very similar, but when the valve does open it really opens
with these two cams. To make big horsepower.

The glide has to go. The car will be a snail reguardless of what you do, by using the glide.

The DCR theory calc will not tell you if it will run on pump gas.
It will be boarder line reguardless. If it pings @ 11:1 take the heads off and take more off the domes, by hand.

[BlackoutSteve]

Relax regarding the 'Glide!
I have accepted the fact that it is not the right transmission and when the time (and money) comes, a TH400 will replace it.

Thanks for those cam recomendations, however, I expected from both yourself and Ultradyne to be recomending tighter LSAs because of the 4000lbs weight.
The cam that cam out, the Crane 138101, had a 110° LSA and I was told it was too wide by the engine builder who suggested going to 106° when he learned of the race weight.

I take DCRs with a pinch of salt. I think there are some relevant details they don't consider. Still, they are probably OK to use for a rough indication.
Perhaps I should consider lowering static to ~10.75 so DCR is in 8.2. Easily done with about ~0.080" off the existing domes.

[pdq67]

Please call UDHarold here at 662-562-4933 and flat ask him to spec a cam for you.

And if you do, please say hello from ol' pdq67 for me.

You can't go wrong with a UDHarold spec'd cam, imho.

pdq67

[BlackoutSteve]

I just did.. That's this post.
viewtopic.php?f=1&t=34693&view=unread#p419679

[pdq67]

Well then, how is Harold?

I hope fine.

pdq67