There was a guy with a low mileage 95 RX7 on here that had a naturally aspirated LT1 making close to 650rwhp. Forget his name but you might do a search.

I also believe Joe Overton said he made over 600rwhp NA, his best run was a 9.7 .

There are SBC's making alot more than 600rwhp NA, so who says a block with the same bolt pattern cant do similar? If you have the money, you can get SBC heads to work on the reverse flow cooled LT1.

 

You might want to read this thread..... Original poster indicates he rode in a 650rwHP NA LT1, saw the dyno sheet for it, and is having a duplicate built for himself.

Time will tell.

"guy with a low mileage 95 RX7" sounds like "jimlab", mentioned in a post above. His engine made 650flywheelHP, and as far as I know, it isn't even in the car yet. I think he's somewhere around $35,000 and counting.

 

I totally disagree, if I use a LT1 block, opti, and convert a set of say brodix track 1s to reverse cooling... Its still a LT1 to me. If it is now considered a Gen 1 engine since i have gen 1 heads, I'd go and buy an Iron Eagle or Little M block, dist, etc.

Just My $.02

 

Why not? I think it is.

Jim hit 650+Fwhp with 23* stuff, Alan hit 568Rwhp with 15* stuff and a LT4 intake...

If all your talking about is using the Lt1 block and not heads, a set of sb2.2, Doms, or Brodix Canted Valve head all flowing around 400cfm or better could do it with properly matching valvetrain, intake, and bottem end...

 

I agree, along with a bad *** ignition and aftermarket computer (Accel Gen IV DFI) I think it would be pretty easially done. The only "LT1" part would be the block. And I wouldn't expect that to last much longer than a season or two. With the amount of compression it would take (16:1 or so) the tops of the cyl bores will mushroom out. It can be done, it is just not cost prohibitive to do it.

 

Why would "the tops of the cyl bores will mushroom out." I've seen an 1,125hp LT1 engine torn down, no block fill, more than 20# of boost, and there was no problem with the tops of the cylinder bores. The LT1 block is incredibly strong for a "production" piece.

And I think you meant to say:

It can be done, it is just not cost effective to do it.

 

why spend soo much money?wouldnt it just be cost effective to buy all 1st. Gen stuff and work with that?is it possible to stuff a Big Block into an F-Body?

 

why spend soo much money?wouldnt it just be cost effective to buy all 1st. Gen stuff and work with that?is it possible to stuff a Big Block into an F-Body?

 

its possible to use a SBC or a BBC in a 4th gen, but each has its own level of fabrication

 

what kind of modifications would need to be done for an SBC?i thought they had the same motor mounts and ****, should just drop right in right?

 

Let me throw in my $0.03 just for grins...

My engine cost a pretty penny, but a lot of that went into parts that most people who weren't psychotic about weight savings (or putting it into a sub-2,800 lb. car that had 50/50 weight balance originally) wouldn't think twice about. How many people really need a 36 lb. billet crankshaft? 505 gram billet rods? Titanium valves? So eliminating the exotic parts and the money that Mark Montalvo screwed me out of, let's call my engine a ~$20-25k "investment", including engine management. (or , depending on how you look at it...)

A few pictures for anyone not yet familiar with it...
http://www.rx7club.com/forum/attachm...postid=2207471
http://www.rx7club.com/forum/attachm...postid=2207479

Thanks mostly to Mark's delays and parts I paid for but didn't receive, it still hasn't been final tuned, or even run since it was last on the dyno in April of 2002. Yes, it has been a long time. However, I just got the engine last October after a long battle with Mark to release custody of it so B&B could ship it as-is (pretty much untouched since that dyno session), and it was not in a state where it could be run when it was received, not to mention missing parts I paid for... but I digress.

Regardless, it made 640.8 hp @ 6,600 rpm, before peak power, and 636.7 hp @ 7,400 rpm, after peak power, or rather, where peak power should have been. A big dip in power through the peak zone was caused by the Opti-spark, which apparently couldn't light off the mix reliably. Another Opti-spark was tried with the same results, so I'm in the process of converting it over to running LS1 coils in my spare time. While it's only speculation, Brian (B&B Performance) estimated that the engine had ~680 horsepower in it after tuning, and probably would have made 660 as-is with a properly functioning ignition. Even using Brian's high estimate, we're still "only" talking about ~580 RWHP 15% drivetrain losses. I'll be happy with 550-560, since 500 was my original goal. Remember, it's a ~2,750 lb. car.

The dyno results I received...
http://www.rx7club.com/forum/attachm...postid=2206653

My AFR 215cc raised runner heads flow in the 335 cfm range, and I have about $5,000 tied up in the heads, not including the Ti valves or Crower shaft rockers. My Hogan's intake was $2,850, and is probably a significant contributor to my power numbers. Bottom line, you'll likely have $8,000+ into the top end of any engine capable of breaking 700 flywheel hp NA, unless you have the room to run a set of SB2.2 or Dominion heads with a carb, or you do all your own porting and really know what you're doing. The point being that there are SBC heads out there that will flow enough air for 700+ flywheel horsepower when strapped onto an LT1 block, so it is possible.

My solid roller cam specs are 260/267 @ 0.050", 0.686"/0.686" lift at the valve, on a 112 lsa. Static compression is 11.4:1, dynamic is obviously lower, it's definitely a pump gas engine. However, that doesn't mean that it's a street engine. Vacuum is around 11 in. and it idles at around 1,100 rpm, I'm told. I'll have to use a vacuum pump to run my brake booster, and it's not exactly a traffic crawler when it comes to street manners, I'm sure. Consider that an engine that would make the power required for 600+ RWHP would have to have an even larger cam (see the specs for the 414 CID LS1 listed previously), and higher compression, and you'll see that 600+ RWHP NA is not a very realistic goal for a street engine. Certainly attainable, and yes, you could probably drive it on the street, but that doesn't really make it a street engine. Mine is borderline, helped only by the fact that I'll be able to fill up at gas stations like everyone else.

If I had it to do over again, and had the prescience to know that an aluminum Motown block would be released while I was waiting on my engine to be finished, I would have scrapped the LT1 platform altogether (I have nothing left in my engine that is an off-the-shelf LT1 part except the block and the front cover) and gone with an aluminum Motown block for my weight savings, saved the money on the crankshaft, built a 454 short block and thrown a set of 15- or 18-degree heads on it and strapped a supercharger on the front. I would have spent a bit less, had more power, better street manners, and even with the S/C, probably would have ended up at about the same weight, or only a bit heavier.

Lesson learned... never commit to current technology, there's always better stuff coming next year.

 

Jim was there a reason given that the opti would not fire?, sure it was not a coil or MSD issue? I am shooting for very high 600's at the flywheel with my combination, am gonna try it with stock LT1 edited ecm and opti, max power will be under 7000 rpm, so I see no need for DFI or a FAST. My Dynamic compression is around 9.2(If I remember correctly), it will be a pump gas engine. Do I need to look at a LS1 coil setup?, will my factory ECM run it? I have read a little about the LTCC setup, not much though. I think mid 500's at the wheel is possible with 23* heads, Not stock castings though. And not with a stock intake, 383 or larger. Whats the most anyone has seen on a stock type engine management??


David

 

well for one thing the distributor wont fit under the cowl if you just try to plop it in. Then there is dealing with the computer stuff if you are stayin fuel injected. im sure there are other concerns as well, but im not there yet, mayb ill be fast enough to worry about it next year

 

I don't know what they were using for a coil or ignition source. Brian said that they were getting spark scatter at high rpm with the brand new vented Opti I sent down, and that they then tried another new Opti with the same results. I asked if I couldn't just try another but he advised against it and recommended going with the crank trigger/cam sync setup. He didn't have a specific explanation for why it wasn't working, though.