Don Terrill’s Speed-Talk

I'll play a little

CamKing wrote: For the average application I need,
Bore: 4.030"
Stroke: 3.622"
Rod length: 6.1"
Comp Ratio: 10:1 but can be increased a bit. Fuel is at best 93 octane pump gas.
Rocker Ratio: 1
Valve diameters: 2x1.6" intakes, 2x 1.3" exhausts
Intake CFM @ 28": 50@050, 100@100, 150@150, 190@200, 235@250, 280@350, 310@350, 335@400, 345@450, 345@500
Exhaust flow CFM 28": 45@050, 95@100, 145@150, 190@200, 225@250, 245@300, 260@350, 265@400, 265@450
Tappet type and size: DOCH, direct acting hydraulic flat tappet, 35mm diameter
Intake Manifold: 54mm ITBs, 5" runner length, total intake tract length 9"
Carb size: FI
Exhaust type and size: 4-1 headers, primary runner 23 inches with step from 2" to 2.125" in the middle. The primaries aren't exactly equal length. Collector about 14 inches long before cross-over
Desired peak HP RPM: 7300 rpm? The objective is to get maximum average power 5000-8500 rpm
Max engine RPM: 8500 rpm
Stall Speed(or corner RPM): Might downshift to about 5500 rpm but let's say 5000 rpm, if I understadn this question correctly.
Application: Normally aspirated 6.1L V8 for a 3600 lbs sports/touring car
Use: Sports car for street, road trips, not logical purpose or use, dyno queen, little drag racing, a hobby car.

Let's make this a bit more interesting. Suppose that I have an adjustable LSA, and want to build an engine that could be run both normally aspirated (by opening and closing the exhaust valve later, thereby increasing the overlap and increasing the efficiency) or turbocharged (by opening and closing the exhaust valve earlier, thereby reducing the overlap and providing more energy to the turbine; by opening and closing the intake valve later, thereby reducing the effective compression at mid range to hold back knock). Furthermore, suppose that I'm already leaning towards the following kind of profiles: intake 262@0.01", 240@0.05", 0.48" lift; exhaust 257@0.01", 235@0.05", 0.44" lift. Is it possible to build such an adjustable-LSA, dual-use engine without too big of a compromise and would those kinds of profiles get me there?

Bore: 4.030"
Stroke: 3.622"
Rod length: 6.1"
Comp Ratio: 10:1 but can be increased a bit. Fuel is at best 93 octane pump gas.
Rocker Ratio: 1
Valve diameters: 2x1.6" intakes, 2x 1.3" exhausts
Intake CFM @ 28": 50@050, 100@100, 150@150, 190@200, 235@250, 280@350, 310@350, 335@400, 345@450, 345@500
Exhaust flow CFM 28": 45@050, 95@100, 145@150, 190@200, 225@250, 245@300, 260@350, 265@400, 265@450
Tappet type and size: DOCH, direct acting hydraulic flat tappet, 35mm diameter
Intake Manifold: 54mm ITBs, 5" runner length, total intake tract length 9"
Carb size: FI
Exhaust type and size: 4-1 headers, primary runner 23 inches with step from 2" to 2.125" in the middle. The primaries aren't exactly equal length. Collector about 14 inches long before cross-over
Desired peak HP RPM: 7300 rpm? The objective is to get maximum average power 5000-8500 rpm
Max engine RPM: 8500 rpm
Stall Speed(or corner RPM): Might downshift to about 5500 rpm but let's say 5000 rpm, if I understand this question correctly.
Application: Normally aspirated 6.1L V8 for a 3600 lbs sports/touring car
Use: Sports car for street, road trips, not logical purpose or use, dyno queen, little drag racing, a hobby car. Maybe little turbo down the road with an adjustment of the LSA.

ptuomov wrote:I'll play a little

258/248 @.050"
.488"/.462" Lobe Lift
98 ICL
110 ECL

CamKing wrote:

ptuomov wrote:I'll play a little

258/248 @.050"
.488"/.462" Lobe Lift
98 ICL
110 ECL

Thanks. I was guessing you'd recommend more duration that other people are running with this engine, but it makes logical sense given the rpm range.

Could I turbocharge an engine with those cams, if I'd spread out the LSA?

ptuomov wrote:

CamKing wrote:

ptuomov wrote:I'll play a little

258/248 @.050"
.488"/.462" Lobe Lift
98 ICL
110 ECL

Thanks. I was guessing you'd recommend more duration that other people are running with this engine, but it makes logical sense given the rpm range.

Could I turbocharge an engine with those cams, if I'd spread out the LSA?

Yes, but you'd probably want to cut the duration back to help with the transition, and let the turbo pressure extend the top-end. Something around a 252/248.

BTW, what's the engine?

CamKing wrote:

ptuomov wrote:

CamKing wrote: 258/248 @.050"
.488"/.462" Lobe Lift
98 ICL
110 ECL

Thanks. I was guessing you'd recommend more duration that other people are running with this engine, but it makes logical sense given the rpm range.
Could I turbocharge an engine with those cams, if I'd spread out the LSA?

Yes, but you'd probably want to cut the duration back to help with the transition, and let the turbo pressure extend the top-end. Something around a 252/248. BTW, what's the engine?

It's a little long-term build that I have going on on the slow burner. A 32V V8 based on the Porsche 928 S4 motor. I'm in the process of ordering the crankshaft, have the pistons and ring packs, have rods which need a small tweak to work. A friend will be fabricating a adjustable center sprocket for the intake cam, he's got a solution from a motorcycle engine. Bought the heads from another friend who moved on from Porsche's to BMWs. Been trying to get someone to make me a dry-sump pan/pump combo that works with the A/C compressor still installed, but that's almost a year into the project and no progress so far. One of the forum members here is making me an ITB system, with a plenum that should be able to work with both N/A and turbo if need be. But still, realistically, it's not going to be ready tomorrow.

Rick360 wrote:

UDHarold wrote:There are some cam companies that claim that Intake Closing is the most important event in a cam cycle.
I claim it is the 3rd most important event, beating only where the Exhaust closes.
UDHarold

Harold,
What order of importance do you place the events? Why that order?

Thanks,
Rick

This question and repose always puzzles me, I don't think you can put any importance on any one of the four events.

My very limited cam knowledge tell me that where these four events occur is far more important than any of the single events.

ptuomov wrote: A 32V V8 based on the Porsche 928 S4 motor.

Here's some profiles I made for the Porsche Cayenne DP project.

H71500EX1: 285°@.004", 240°@.050", .500" Lift
H72500EX: 288°@.004", 243°@.050", .500" Lift
H72500EX3: 291°@.004", 245°@.050", .500" Lift
H73500IN2: 294°@.004", 249°@.050", .500" Lift
H74500EX: 296@.004",° 249°@.050", .500" Lift
H74500IN1: 297°@.004", 251°@.050", .500" Lift
H75500IN: 300°@.004", 255°@.050", .500" Lift

With the variable timing, I'd look at using the H75500IN on the intake, and the H74500Ex on the exhaust.

CamKing wrote:

ptuomov wrote: A 32V V8 based on the Porsche 928 S4 motor.

Here's some profiles I made for the Porsche Cayenne DP project.

H71500EX1: 285°@.004", 240°@.050", .500" Lift
H72500EX: 288°@.004", 243°@.050", .500" Lift
H72500EX3: 291°@.004", 245°@.050", .500" Lift
H73500IN2: 294°@.004", 249°@.050", .500" Lift
H74500EX: 296@.004",° 249°@.050", .500" Lift
H74500IN1: 297°@.004", 251°@.050", .500" Lift
H75500IN: 300°@.004", 255°@.050", .500" Lift

With the variable timing, I'd look at using the H75500IN on the intake, and the H74500Ex on the exhaust.

It's not variable timing in the sense that LSA is not adjustable when the engine is running (not the 968 solution). What I mean that the LSA can be changed conveniently when tuning and if/when putting turbos on.

Suppose that the intake cam has the following spec:

Max lift 0.518
Duration
284° @ 0.01"
274° @ 0.02"
260° @ 0.04"
256° @ 0.05"
235° @ 0.10"
217° @ 0.15"
200° @ 0.20"
165° @ 0.30"
122° @ 0.40"

What's the best exhaust cam lobe to match this intake cam in the engine I described a couple of posts ago?

quite a bit shorter than Cam Kings R&D cams
Is this for the turbo?
do you have head flows?
thanks for the clarification on cam adjustability
same compression if turbo?

ptuomov wrote:Suppose that the intake cam has the following spec:

Max lift 0.518
Duration
284° @ 0.01"
274° @ 0.02"
260° @ 0.04"
256° @ 0.05"
235° @ 0.10"
217° @ 0.15"
200° @ 0.20"
165° @ 0.30"
122° @ 0.40"

What's the best exhaust cam lobe to match this intake cam in the engine I described a couple of posts ago?

My Ex lobe: M74500Ex
284° @ 0.01"
272° @ 0.02"
256° @ 0.04"
249° @ 0.05"
224° @ 0.10"
203° @ 0.15"
184° @ 0.20"
147° @ 0.30"
103° @ 0.40"

CamKing -- Thanks a lot, that's very useful and detailed info. Do I understand correctly M product code means mechanical? Would these run well on a hydraulic lifter? Would the H74500Ex that you listed in your Cayenne DP (Diesel Power?) cam post work, it looks similar to that profile? Or am I just assuming untrue things about your product coding system?

I'm guessing Mike did the cams for the privately entered V-8 Cayenne-powered Daytona Prototype racer that laid waste to the opposition (including, embarrassingly, the Porsche factory 6 cylinder entries) in the Daytona 24 hour race a couple of years back...

MadBill wrote:I'm guessing Mike did the cams for the privately entered V-8 Cayenne-powered Daytona Prototype racer that laid waste to the opposition (including, embarrassingly, the Porsche factory 6 cylinder entries) in the Daytona 24 hour race a couple of years back...

Daytona Prototype makes a lot more sense than turbodiesel I guess. Learn something new every day!