Fuel economy vs gas prices

[THE PUNISHER]

The Delorean in back to the future required 1.21 Giggawatts for time travel. It was originally powered by plutonium , well maybe plutonium is available at every corner store in 1985 futureboy , but here in 1955 it's a bit hard to come by

then they changed to the MR. Fusion system..it worked a lot better.

Then doc brown built a train to travel through time and he had 2 kids.

So I think you can see where I am going with this.

[Atilla the Fun]

So, the rod/piston/crank combo works perfectly, but out of the box Vortec heads measure near 61cc, assuming you mean the 170cc truck version, not the newer raceshop 185 or 205 versions. The 185s are too big for what you're hoping. Yes, the 2 piece seal thing is the same, but you will need bearing spacers for the mains. I think you can get these from King, and from Comp cams. That surprised me.
If you go ahead as planned, mill the domes off and it will improve flame travel. Plus it will then balance lighter. You're putting an awful lot of money in the shortblock to be cheaping out on the heads. Why not some AFR 180s?
With the high compression and a late intake closing, you are fixing the dynamic compression to be similar to a 9:1 with traditional intake closing, so you lose the part-throttle benefit you were trying to build in. I think you might look into COMP's Cam-Correct system.
Tall axles like 2.9:1 plus high dynamic compression equals detonation. For less money than your proposed build, you could pick up a good used 5.3 like I did, as these are good well past 200,000 miles.
The entire 5.3 conversion would be less than your vortec build, and then add you some boost. But if you plan to boost an LS, you may as well get a 4.8, and leave the 3.3 gears alone.
What's the tire size, anyway?

[THE PUNISHER]

on a serious note

u can get a 5.3 in an Aluminum block

you can't in a 4.8


the weight alone is worth it.

[Atilla the Fun]

P.S. I mean the 4.8 won't like a 2.88:1 with a 0.696:1, a Jaguar is too heavy for that. On another note, I concede that plenty of guys claim to be running 10.3:1 Vortec 350s on 91 octane, but where's the proof?

[Atilla the Fun]

You can put the 4.8 crank and rods in the alum 5.3 block

[Atilla the Fun]

the aluminum block 5.3 can be bored to 5.7. The iron block 5.3 can be bored to 6.0

[fieroguru]

P.S. I mean the 4.8 won't like a 2.88:1 with a 0.696:1, a Jaguar is too heavy for that. On another note, I concede that plenty of guys claim to be running 10.3:1 Vortec 350s on 91 octane, but where's the proof?

My vortec head SBC Fiero has been running 10.2:1 compression and 89 octane for 25K miles over the last 5 years. That is without an egr as well.

[Atilla the Fun]

ok, what's your cam? your spark advance curve? your elevation? these things make a difference. Exhaust manifolds or headers? But congrats in any case!

[fieroguru]

I live in central KY at about 1000 ft elevation (91KPA is WOT), but the car pulled a 1000 lb trailer from MI to FL, and has been driven through WI, MI, IL, IN, OH, KY, TN, AR, AL, GA and FL

ZZ4 roller cam.
Advance below 80KPA is mostly stock B-car with cast iron LT1 heads.
At 90 KPA and higher I run 31 degrees starting at 1800 rpm and get to 33 at 5600 (I can go higher, but it does not result in any more HP).
Exhaust manifolds are Speedway Motors cast stainless steel tru-rams (similar design as Rams Horns).
Engine runs 180 degress idling, spinning 3K or stuck in stop/go traffic for hours on end (Hotrod Power Tours really test your cooling).

When it was on the dyno, I just left it idling in between the dyno runs (18 in about 1 1/2 hrs).

At 80 MPH the engine pulls down 21-23 mpg with the lack of egr holding me back. At 65 to 70 MPH engine pulls 26-30 kpa...

[Atilla the Fun]

Maybe you could modify a 75mm EGR spacer for a 5.0 Mustang, it should have enough meat to go 90 mm.

[fieroguru]

Maybe you could modify a 75mm EGR spacer for a 5.0 Mustang, it should have enough meat to go 90 mm.

I will keep that in mind. The Ramjet uses the 75mm throttle body, so the mustang one should work with some mods.

[The Dark Side of Will]

What's the bolt pattern on your TB? Northstars up to '99 used an EGR spacer for their 75mm TB's.

[THE PUNISHER]

I live in central KY at about 1000 ft elevation (91KPA is WOT), but the car pulled a 1000 lb trailer from MI to FL, and has been driven through WI, MI, IL, IN, OH, KY, TN, AR, AL, GA and FL

ZZ4 roller cam.
Advance below 80KPA is mostly stock B-car with cast iron LT1 heads.
At 90 KPA and higher I run 31 degrees starting at 1800 rpm and get to 33 at 5600 (I can go higher, but it does not result in any more HP).
Exhaust manifolds are Speedway Motors cast stainless steel tru-rams (similar design as Rams Horns).
Engine runs 180 degress idling, spinning 3K or stuck in stop/go traffic for hours on end (Hotrod Power Tours really test your cooling).

When it was on the dyno, I just left it idling in between the dyno runs (18 in about 1 1/2 hrs).

At 80 MPH the engine pulls down 21-23 mpg with the lack of egr holding me back. At 65 to 70 MPH engine pulls 26-30 kpa...

Beautiful Conversion!

[fieroguru]

What's the bolt pattern on your TB? Northstars up to '99 used an EGR spacer for their 75mm TB's.

The Ramjet uses the 3 bolt LS1 style throttle body. Is the N* similar? Anyone have a pic of this egr plate?

[fieroguru]

Beautiful Conversion!

Thanks!

The 2nd cut to sheet metal happened last year when I cut the hole for the cold air intake (1st cut was to relocate the harness to the shifter cable area in 2005). I had to notch the deck lid for the intake, but if I set it up for DIS I can flip the intake and it will eliminate the need for the notch. Everything else clears without cutting or denting of the sheet metal... even the mechanical waterpump.

[The Dark Side of Will]

So, the rod/piston/crank combo works perfectly, but out of the box Vortec heads measure near 61cc, assuming you mean the 170cc truck version, not the newer raceshop 185 or 205 versions. The 185s are too big for what you're hoping. Yes, the 2 peice seal thing is the same, but you will need bearing spacers for the mains. I think you can get these from King, and from Comp cams. That surprised me.
If you go ahead as planned, mill the domes off and it will improve flame travel. Plus it will then balance lighter. You're putting an awful lot of money in the shortblock to be cheaping out on the heads. Why not some AFR 180s?
With the high compression and a late intake closing, you are fixing the dynamic compression to be similar to a 9:1 with traditional intake closing, so you lose the part-throttle benefit you were trying to build in. I think you might look into COMP's Cam-Correct system.
Tall axles like 2.9:1 plus high dynamic compression equals detonation. For less money than your proposed build, you could pick up a good used 5.3 like I did, as these are good well past 200,000 miles.
The entire 5.3 conversion would be less than your vortec build, and then add you some boost. But if you plan to boost an LS, you may as well get a 4.8, and leave the 3.3 gears alone.
What's the tire size, anyway?

Tire size is 215/70-15.
We already have the 400 block, the 283 crank and the production Vortec heads. 61cc chambers instead of 65 isn't really a problem because I could use the flat top version of the same KB piston with no problems or additional costs.

How much would you charge to work through this set of heads?

The AFR website isn't available right now, or I'd calc the DCR of the 347 they built. It didn't have a whole lot of cam... about what a stock LT1 has, IIRC?
What I'm insterested in finding out is if the long rod engine combo redefines the DCR assumptions that people have formulated over years of dealing with 350's and engines with simiilar relatively short rods.

What I think would be a killer engine to build, especially for a Fiero, would be a Chevy 302. It would be a roller 350 block, 3" crankshaft from L99 V8, 6.375 rods and pistons for a 383 with 6" rods. The rods are an obstacle right now because I haven't found any small Chevy rods that long, but maybe BBC rods with aluminum spacer bearings would work...
That would get the rod ratio up to almost 2.2.

[darkhorizon]

Timing advance is a decent way to make up for crappy compression ratios.

[The Dark Side of Will]

Maybe the chamber volume will be a small problem.
The supposed "flat top" actually have 7cc valve reliefs. With 61 cc chambers, this would drop my SCR down to 10.5. That's lower than I want to go. Hot Rod Magazine built their 347 with 11.0 and aluminum heads. It ran 87 octane on the dyno. Even with iron heads and in a car, I think a similar short block could run 11.0 on 93.

The -3.25cc slugs have solid domes, so I could cut them to get down to 11.0 if necessary.

AFR's website is back up, so I'll look at that engine again. The Hot Rod 347 was running a Comp 270H-R10 cam. That stick has 270 degrees total duration and 110 lobe sep. The 270 duration is of course in crank degrees, but for some @$$ backwards reason, the lobe sep is always in CAM degrees. The lobe centers are actually 220 crank degrees apart.
@$$uming is was installed straight up (since nothing is mentioned about cam adv/ret), the IVC is 55 degrees ABDC. At this point, the crank pin has risen 0.693, the piston has risen .550 and the DCR is 9.18.

A conventional 350 with the same cam and SCR would have a DCR of 9.26, so the 347 configuration gives a slightly lower DCR at the same SCR (IE, the SCR/DCR ratio is higher and the engine is more high RPM biased--purely from its geometry).

That may sound like race gas territory according to conventional wisdom, but the HR 347 ran on the dyno on 87 octane. Even if it needed 89 on the street, that's pretty dam crazy.

Obviously, they mentioned nothing about coolant temps or IAT or quench, but I think that we can assume these variables were optimised. The question then becomes: How much could they have cheated? Were they running 160 degree coolant temps? Feeding the intake through an air conditioner? Was Smokey Yunick around?

[The Dark Side of Will]

What's the bolt pattern on your TB? Northstars up to '99 used an EGR spacer for their 75mm TB's.

The Ramjet uses the 3 bolt LS1 style throttle body. Is the N* similar? Anyone have a pic of this egr plate?

No, the Northstar uses a square bolt pattern.

[Aaron]

What's the bolt pattern on your TB? Northstars up to '99 used an EGR spacer for their 75mm TB's.

The Ramjet uses the 3 bolt LS1 style throttle body. Is the N* similar? Anyone have a pic of this egr plate?

No, the Northstar uses a square bolt pattern.

Not sure what N* you're looking at, as they use the LS1 style 3-bolt. My N* TB:

http://img.photobucket.com/albums/v336/ ... ine108.jpg
http://img.photobucket.com/albums/v336/ ... ine106.jpg

[pictures edited to links]