Fuel economy vs gas prices

[THE PUNISHER]

I won't mod my car due to miles ....it's got 180,000 miles on it , still tight and drives well... BUT.. if you wanted too ...wow.. the power u can get.

a TDi mated to a 6spd with a Reflashed ecu and injectors would be a high 14 sec car...not earth shattering , but no slouch either.


Diesel sounds badass uncorked!

[The Dark Side of Will]

I'd still like to build this engine initially to be as close to the magazine build as possible (270H-R10 cam), but this new info alters the subsequent development plan. I'm pretty confident the engine will run on 93 just fine. With Atilla's info, I can change the cam for a more aggressive DCR as part of the development effort. Thanks.

In looking at the development path, I may change my mind a little bit.

The HR build ran 11.0:1 SCR with 8.5 DCR. By upping the SCR to 11.50 and using the same cam, I can build an engine with 8.8 DCR.
If that's too much for iron heads, I can retard the cam 3 degrees and get down to 8.55. Obviously I could also see how it runs at 1 or 2 degrees retard. I could even advance a couple of degrees also. Two degrees of advance would put me to 8.95.

If I run 11.25:1 SCR, then 2 degrees of retard on the 270H-R10 will put me at the same DCR as 11.0:1 with the same cam straight up (8.46). Three degrees of advance will put me at 8.85. Atilla's 258 degree recommended cam installed 3 degrees retarded will also put me at 8.85. I could use the two sequentially and just keep bumping the cam timing by a degree at a time to see how far it can go.

Atilla, can you make a recommendation for an adjustable timing drive? Two piece timing cover?

I ALSO need to look at how these different durations will interact with the TPI and move the torque curve around.

IOW, I think that if I build with a higher SCR, my development path has more options to go higher, but does not close off any options to gracefully degrade to a safer configuration.

[Atilla the Fun]

I suspect your 270HR10 is both an off the shelf grind and has more than .480" intake lift. As to what everyone is mistakenly calling DCR, the accorate term should be Theoretical compression ratio. This is determined by either figuring or measuring how far back up the cylinder the piston is when the intake valve closes, and recalculating your static compression ratio with that reduced stroke. There are other methods, but the result is the same. What everyone but Will needs to be concerned with is cranking compression, but bear in mind that this can be affected by how fast your starter turns the engine. Again Will, your engine won't have as broad of a powerband as the one you are referencing, as your heads will never flow as well, and If you want lobes closer to their specs, but with proper lift for your heads, I'll give you a half dozen tomorrow. On another note, wouldn't an ecotec be just as thrifty but even more fun than swapping a VW TDI?

[THE PUNISHER]

No way in hell any 4cyl motor on the market is even close to a TDI...


my Honda non Vtec D15 got 1/2 the mileage..

[The Dark Side of Will]

I suspect your 270HR10 is both an off the shelf grind and has more than .480" intake lift.

Yeah, Summit has it and lists lift as .500.
I appreciate your help.
I need to start with something that I can install close to straight up with the same DCR as the magazine engine, but have room to retard to reduce DCR if I have detonation issues with the iron heads + coated pistons. If I don't have detonation problems, then I can advance it and if I advance it several degrees without issues, then I can move to a shorter duration.

Yes, as I'm using the term, DCR means the compression ratio calculated using the cylinder volume at IVC.

On another note, wouldn't an ecotec be just as thrifty but even more fun than swapping a VW TDI?

Maybe a direct injection Ecotec without the turbo and with custom pistons to push the SCR to 13:1 might come close to a TDI, but that would mean getting rid of a turbo in favor of gas mileage. I'd rather have the turbo AND the fuel economy! Chipped TDI's can push 200 HP. With the common rail injection, they're just as upgradeable as the Cumminses, the PowerStrokes and the Duramaxes.

The diesel's natural advantages over gasoline engines are compression ratio and pumping losses. Because the diesel is unthrottled, it doesn't have to pull air through a throttle valve, so it has less parasitic pumping losses. Also, because the intake charge is compressed from and subsequently expands back to the same pressure, the expansion ratio and compression ratio are always the same, even at part throttle.

This is not the case with a gasoline engine. The expansion ratio (from which the engine derives its useful work) can be very different than the compression ratio due to the simple fact that mixture is being compressed from a pressure lower than atmospheric.

[The Dark Side of Will]

If I could build a spreadsheet that could CORRECTLY calculate DCR, that would be fantastic.

IE, I fixed some errors in my Engine Dimensions spreadsheet.

The Hot Rod Mag 347 ran 8.69:1 DCR with 11:1 SCR and cam with 270 duration & 110 lobe sep installed (I am assuming) straight up. It ran 87 octane on the dyno. It had AFR 190 heads for 305 with 56 cc chambers. The pistons were custom JE pieces with ~8cc net dish.

That engine had aluminum heads and uncoated pistons.
I want to build an identical engine except: iron heads and coated pistons.

Risk:

• Reduced heat conductivity of chamber and piston will increase chamber energy to the point of detonation

Mitigation:

• Vortec heads don't flow as well as AFR's, so charge density (and chamber energy) will be lower.
• Run premium fuel only.
• Install adjustable timing drive + two piece timing cover to retard cam to lower DCR and chamber energy

Opportunity:

• Engine can run greater than 8.7 DCR on premium fuel without detonation

Facilitation:

• Install adjustable timing drive + two piece timing cover to advance cam to increase DCR and chamber energy
• Be prepared to change camshaft to one more ideal for power once max acceptable DCR has been found.

With 270H-R10 or similar, the engine will have 8.7 DCR with the cam straight up. Three degrees of retard drops that to 8.48, 3 degrees of advance increases to 8.90.
Atilla's 258 degree cam with 3 degrees of retard would give 8.90 DCR and can go up to 9.29 with 3 degrees of advance.
I don't think the engine will get that far, but the possibility is interesting.

The necessity of using a two piece timing cover will give me problems with the Vortec crank sensor. I'll figure something out for that...

[Atilla the Fun]

All of COMP's street shelf cams have 4 degrees of advance ground in. But almost every chain in the universe will stretch 1 degree's worth in the first 5 minutes of run time, so figure they ran it at 107 degree intale centerline. As to TCR, If you live at higher elevation than their dyno, then you can run more TCR. And elevation isn't the only adjuster, there's also humidity. So, here's some lobe specs for your custom order cam. First, using a 400 block, your part number is 12-000-8, then say 9999/9999-110 for your int lobe/exh lobe-lobe sep.
3108=270=215, 500 lift
intake lobes:
3324=259=210, 474
3326=263=214, 474
3303=265=216, 474
3306=269=220, 474
3307=273=224, 474
exhaust lobes, please use more exhaust duration than intake
3033=264=212, 512
3034=270=218, 521
3035=276=224, 530
3036=282=230, 533
3037=288=236, 536
3313=270=218, 495
3314=276=224, 503
3315=282=230, 510
3316=288=236, 521
3119=280=224, 525
Also, if you have the same intake closing point for 2 cams, and one has less overlap, it will have a higher true DCR at lower rpm, and lesser at higher rpm. The reverse is also true, up to the point that the intake closing point no longer allows adequate cylinder filling.
On a 5.7 liter V8, the Vortec heads are basically all done by 5600 rpm, regardless of how big your cam gets. Thus, for max output, with a thought for emissions but not for mileage, a great cam would be a 3303/3314-110. This is the most cam I would accept for a Vortec-headed 5.7L, If it isn't strong enough, then I'd spend for AFR 180s. That's my 2 cents worth.

[The Dark Side of Will]

Thanks! I may be able to take some time this weekend to really look through that info.

http://www.chevyhiperformance.com/techa ... index.html

Obviously that's not a basic build by any stretch of the imagination and those aren't production Vortec heads either.

How do the Bow Tie heads compare to the production heads?

What flow numbers do you typically see out of production heads?

The car's going to be operated at less than 1,000 ft elevation.

[Atilla the Fun]

Yeah, I remember reading that article with great interest. The best numbers I've ever seen for untouched truck Vortecs are about on par with what I saw on a new SuperFlow 1020 bench after putting good valves in. I switched to a one-piece, stainless, swirl-polished valve with undercut stem and 45 degree seat with 30 degree back cut. With no other changes, I got 188 cfm at 28" at .300" 225 cfm at .400", and 238 cfm at .475". On the exhaust side, I never found a 1.50" setup that suited me. I strongly advise going to 1.60" with a 5 angle valve job, and a bit of porting. I can go into more details if you are going to do so. Details I feel are needed before even taking the heads to the machine shop. As for how the 170cc truck Vortecs compare to the 185cc and 205cc BowTie vortecs, I read all I could find on them the first 6 months after I heard about them, then decided I would rather use other heads and soon forgot. Today, IF I wanted 600 HP as per that article, I would go with Dart Platinum series heads, probably the aluminum 200cc rather than the iron 200cc. The wet flow is proven better, and the combustion chambers are also better.

[The Dark Side of Will]

What do you know about Hank the Crank? When I was spec'ing my Northstar build, I REALLY wanted their ceramic piston pins, but they had apparently JUST gone out of business.

[Atilla the Fun]

Reher-Morrison strongly advocates casidium coatings on wrist pins, especially for 2500-HP engines. Also, I just re-read your first 2 posts on this page, and realized I've failed to answer a couple of questions. One, my experience is that aluminum is the best material for 2-piece timing covers. You'll have less leaking. Two, answering about TPI vs cam timing, for some bizarre reason, the TPI setup seems to like the GMPP H.O.T. cam. It gives up alot of power compared to an RPM AirGap, but it still gives one of the broadest usable powerbands ever found with GM-style TPI. Then again, the stock TPI cams used a late intake closing also. With a new timing chain, the stock I.C. was 36 degrees a.b.d.c. The H.O.T. specs as 38 with 1.5:1 rockers. So, what about an earlier I.C.? You might get better mileage with your 2.88:1 gears, but with your other gears, I feel a later IC could really help. Note that every emissions legal cam has NO overlap at 0.050" tappet rise. The 216/224-110 setup I like meets that criteria. You should get 190 psi cranking, and over 15" idle vacuum.

[The Dark Side of Will]

I'm not going to make 2500 HP with the Northstar--maybe a fifth of that in a couple of years after I get a heads/cams package, build headers, build throttle-per-cylinder intake, etc.

I just wanted the ceramic pins to reduce recip weight by 30-40 g per cylinder. That would let me take close to 150 g out of the crank, which is a worthwhile reduction of MOI.

Here's tidbit on the ceramic piston pins:
http://www.carcraft.com/techarticles/pi ... index.html
Ctrl-F "Ultralloy"

And a picture here:
http://www.carcraft.com/techarticles/pi ... to_06.html

[The Dark Side of Will]

Atilla, what do you know about high nickel 400 blocks and how to recognize them? I've looked up a few things on the net, but I'm seeing conflicting info. My dad has a couple of 400 blocks on the shelf and one in the car and I'd like to know what they all are.

[Atilla the Fun]

To save me typing 9 paragraphs, it'd take a lot less bandwidth if you could just share the casting numbers, or if you want to keep them secret, PM me. But the less-common blocks that are cast from a better mix of metals do exist, and do have advantages. For those playing with 350s, under the timing cover, you should see 010 and 020 cast right together. This means high nickel and high tin. This helps a few things, including resistance to cracking and reduced wear. But EFI instead of the best carburetion will help with wear much more than what metals are in the "iron". Also, for those wanting to be stealthy, the 509 blocks are the ones to look for, they don't have the extra freeze plug boss on each side. However, they usually do have 509 visible around that same area. Lastly, with 400s, do not get a factory 4-bolt-main block, they crack the main web area far more than any other SBC, and I mean FAR easier.

[Blue Shift]

I had a 307 Chevy of all things that had a no bullshit 010 020 clearly cast under the timing cover... It was an OMC 245HP marine motor, though.

[Atilla the Fun]

News to me, but not very surprising, so I don't doubt you.

[The Dark Side of Will]

Interesting SBC rocker arm tech: http://www.circletrack.com/techarticles ... index.html

[Shaun41178(2)]

Not sure where the technology went for that, but crane is no longer around. Still interesting reading though.

Kind of makes me wonder what ever happened to the vented valve technology

[The Dark Side of Will]

Crane's out of business? Holy cow...

[Atilla the Fun]

Yes, but some is back, and someone bought the right to ressurrect the name. Other parts of Crane are permanently dead, and yet other stuff is now under new names, ownership, or whatever. In this case, it really is complicated.
Mikroniting was something I was eager to try.