Gramps

iTrader: (1)

im a subscriber to "superchevy" magazine, and in thier march 07 issue, they have a good article on a corvette L98 engine which they turn from stock to "impressive" their idea is to make the engine look stock as well, they stroked it to 3.75" and bored .030" over. they ported the stock heads and gave them a valve job, ported the plenum, intake manifold and replaced the runners with bigger ones (still looked stock to the untrained eye) and replaced the TB with TPIS's TB and runners. the heads were flowing 260cfm. they had a compcams XR264HR with .487/.495 lift 212/218 duration 110LSA with 1.5:1 aluminum roller rockers. they used Coast High Performance (CHP) kits including a cast crank, forged rods and pistons for the oversided bores and were running 10.6:1 compression. they bolted on a set of hooker headers and a FAST XFI management system and an MSD distributor with the stock valve covers (modified to fit the roller rockers)

"Tuned with the FAST management system, the 383 eventually produced 458 hp and an amazing 534lbs -ft of torque. You read that right, 534 lbs-ft of torque from a small-block. talk about the perfect street stroker. The combination of displacement, cam timing and airflow improvements added up to a gain of 131 hp (measured peak to peak), but the gain exceeded 150 hp out at 6000 rpm. the torque gains were equally impressive, espically given the already torquey nature of the stock L98/ while most small0blockst struggle to produce 500 lbs-ft, this 383 not only produced 534 lbs-ft of torque, but also exceeded 500 lbs-ft from 3200rpm to 4600rpm. It was like we added a blower or turbo kit without anyone being the wiser. TPI strokers rule."

article by Richard Holdener.

im very impressed with that commin from a mild engine upgrade that looks pretty stock to me. if your not a subscriber, you should wait till it comes out and read the article and see the power curves (they are sexy).

1989GTATransAm

iTrader: (3)

Those are good numbers. We have had cars here locally with over 400RWTQ. Kevin91Z had 418rwtq with is 350. Projected that is 492tq at the flywheel with full accessories and not on a dyno stand. Works out to about the same ratio. So yes that is fully doable. With the next round of upgrades to the cars in our club we should do better.

YenkoST

iTrader: (5)

I don't know if I want to believe it or not b/c I have a little bit less compression, AFR heads, bigger cam, and the Holley StealthRam and I know I ain't close to those numbers in my 383. But if they are real numbers and not correct then magazine inflated, that's pretty impressive.

Gramps

iTrader: (1)

you know ive seen some mag inflated articles b4...thats y i buy super chevy, they have real info, and they only deal in chevy so how can one go wrong with that mag. ive also seen threads on here and on the interweb where ppl have more than 500lbs-ft of torque with a HSR and a 383. but im also too lazy to do a search, im sure somebody will coroberate my story.

Orr89RocZ

iTrader: (20)

sounds like way to over inflated numbers for that cam.... tpi shootout had ported trick flows and 236/242 cam with fully aftermarket TPIS setup and made 460hp

Gramps

iTrader: (1)

you know...im not gonna defend the mag company, you cannot compare thier results unless you build the same setup, everybody seems to be slaggin em, well i slag u for not trying to prove them wrong, shame on you.

YenkoST

iTrader: (5)

What rpm did it make peak horsepower?

Its not the torque we are disputing is the horsepower rating. TPI always have impressive torque but as we all know a TPI system stock is a bottle neck and can only flow so much. Therefore, limiting horsepower in the upper rpms.

I know of a 350 with that same cam, edelbrock intake, ported runners, stock heads and his best time is high 14's....low 15's is his average in his truck with a stall and 3.73s on 26" tires. So, its safe to say that he is testing it right now and about to put some headers on it and then tune it back up.

Now, if could be the engine management system helping as well.
Now, AFR did a similiar test but their setup was:
383, 9.5 compression, 218/224 cam, dual plane, 650 cfm carb and made 430hp.

Orr89RocZ

iTrader: (20)

there already has been many many combos built with similar setups and not one has made that power with that cam and TPI. bigger cams and superram doesnt even make 450hp.

1989GTATransAm

iTrader: (3)

VincentZ28 is at 373rwhp with his 350 right now. That projects to 438 horsepower at the motor and with all accessories. I hope to do better when I get on the dyno. I don't see why you guys are so skeptical. Sounds doable to me.

Orr89RocZ

iTrader: (20)

what is his setup? 450+ is doable but i dont see it coming with that small cam.

LT4 hot cam LT1's only put down 350whp with head work. they can rev to 6 grand unlike TPI.

Guest

Ported exhaust TFS heads, Super Ram, headers, I believe G-force T-5, Lunati cam (in the ~226 intake duration range), dont know compression but somewhere in the 10-11 range I'd imagine.

That said, I'd take Holdener's numbers with a small grain of salt. I'm sure they tweaked a few more HP and TQ out of that thing than any normal person would get.

laiky

Ported L98 alluminum heads are what lingenfelter used on his superram motors, in fact when i built my 383 i wanted the cnc lingenfelter heads but they were way more than my afr's (i did not have cores, and the port job was around 1700). I think the head and intake combo is probably well matched. The HP numbers are a result of the torque, if you make huge torque the HP numbers should go up as hp is dependent on torque for a given rpm. Given this is on a dyno, i believe it. It doesn't say anything about average HP or torque though. I think it would be better to compare the averages to other combo's

Americanmouse

iTrader: (7)

I have an article from November of 06' GM High Tech Performance magazine thats called; Something old Something new. They did a similar setup with Accel DFI and got the numbers from a dyno as; 419hp and 486tq. I believe the Chevy article is not only true but TPI'S can produce those numbers and my goal is to make it so.

Orr89RocZ

iTrader: (20)

i finally got my copy of super chevy and read that article

10.6 compression with that small cam 212/218, extrude hone base/plenum, TPIS big tube runners did make some serious power...but the main reason for that was it was ran with NO accessories... even an electric water pump was used! a 350hp LS1 will make near 400hp on a engine dyno with no accessories. but it showed TPI carrying power to 6000 rpms on a 383 with a small cam!! that i just cant believe

put that 383 into a car with all the pullies and drive accessories and it struggle to make 400hp. that car needs more cam.

keywords...SUPER RAM. those setups have way shorter runners than TPI and support high rpm capabilities... combine that with a matching cam and they will make good power to near 6000rpms. TPI cant do it, they arent tuned for that rpm range

laiky

nothing says you can't use a bigger cam!

matt_p

I was about to say that magazines do dyno tests without accesories. So its gross hp and torque.

Gramps

iTrader: (1)

you know when i read the mag i was wondering why they didnt use a bigger one, i guess they wanted some fuel economy or keep it stock or something. thats the cam it came with, somebody upgraded the cam before superchevy got their hands on it. and ya i forgot to say that thers no accessories on that motor, but i woulda thought that to be standard from a magazine ya know

im gonna be buildin up a motor soon, i think mayb ill try and do the same thing as the mag, see what i can get, i prob cant get as good a port/polish tho, which will be the limiting factor for the torque.

Orr89RocZ

iTrader: (20)

i wanna know how much those ported L98 heads were...cuz i would love to have L98 heads on my motor build...so i could still call it a L98

HD4mula

Funny how people say "..because I can't make those numbers then they also can't make them".... or "because I have better heads, cam, bolts I should make more but I ain't so they can't..". Many will have better engines than yours and may make more power with less parts. The hardware is only the body. The life and soul is the tune. They have experts XFI tuners tuning those engines. Get them to work with you and you may get better results. That's what I beleive they can take every little bit of HP in those engines. And of course no accesories help too

Grim Reaper

First, there is a BIG difference between a "bare engine dyno" with no accessories and the typical dyno numbers people get from a chassis dyno. Heck, even the car manufacturers stopped using "gross" HP almost 35 years ago.

If there are any old timers (i.e. older than 50), they will remember there is about a 25% difference between NET & GROSS HP. So that 458 GROSS HP & 534 GROSS TQ, becomes 343 NET HP & 400 NET TQ.

Second, even when comparing chassis dynos, I've seen different dynos produce different numbers from the same vehicle, even after you adjust for air temp & humidity. There is nothing saying that engine on a different engine dyno would even give the same numbers.

But to compare NET HP to RWHP, take off another 20% (typically the difference between NET HP and the RWHP you would get with an 4L60 car). Now that 343 NET HP & 400 NET TQ becomes a more realistic 275 RWHP & 320 RWTQ.

NOW those numbers look right in line what I would expect from those modifications.

Bottom line, the magazine wanted an article to sell magazines and needed some "zing". So they chose a method of showing the data which got peoples' attention. And it certainly did.

Had they installed this engine in a car and said "275RWHP and 320RWTQ from a chassis dyno", it would not have sold as many magazines, and we wouldn't be discussing it here. We would have said "What's so special about that"?

I say, "Let's forget all the tricky BS garbage used to sell magazines. Install that engine in a car and take it to the track, and let's see what it REALLY can do".

LB9GTA

iTrader: (1)

Well said!

Gramps

iTrader: (1)

whats referred to when you say GROSS hp and NET hp? net has accessories? does one have the taxes deducted?

Justin86camaro

ok i know this is gonna be a duh for yall but i have a 73 sbc. what exactly is a l98 motor?

Gramps

iTrader: (1)

L98 motor is the engine code, like LS1 or LT1, camaros came with L98 engines(as well as other engines, but the L98 is a 350), which refers to the longblock package. the L98 is a 350, the LB9 is a 305. your engine prob had an engine code before you stripped it out of whatever you stripped it from.

Grim Reaper

1971 was the last year for "GROSS" HP ratings. (Though I might be off one year). GROSS HP was a "bare engine" with no accessories and used open headers. NET HP was all accessories and full stock exhaust. 1972 was the first year NET ratings were used as well as more emissions equipment like a smog pump.

1973 was the first year when vehicles had to run on unleaded gas (and there was no premium version at that time), this caused a reduction in compression ratios and a further reduction in HP.

Because all of these things happened at the same time, most people attribute the massive reduction in HP to lower compression & smog equipment; which did have a noticeable effect. But, there was also a change in the way HP was rated (which most people either forget or are not aware of).

When the first LT1s were installed in the Corvette & F-bodies, they were a number of magazines that tested the "new" LT1 in comparison to the original LT-1 from 1970 and the "new" LT1s were quicker than the original.

The new LT1s (as installed in the 1992 Corvette) was rated at 300 HP (275HP for the 1993 F-bodies), yet the original LT-1s were rated 360 HP in a 1970 Camaro (I forget the rating for the 1970 Corvette). People were saying the "new" LT1s were "under-rated" and thus why it was quicker than the original LT-1s.

But the truth is, the "new" LT1s were rated using NET HP, and the originals were rated with GROSS HP. Had the original LT-1s been rated with NET HP, it would have been closer to 270 HP (instead of 360HP).

Lastly, when looking at Big Blocks from the late 60s/early 70s, these were ALWAYS under-rated for insurance purposes. The original Hemi was only rated at 425HP, but was actually closer to 525 GROSS HP. Same with the Chevy L88 427s and the Ford Boss 429s.

But, those "under-rated" HPs used on the big blocks is actually close to the NET HP rating used today.

There was also a question of how the NET HP rating is derived. In the past, manufacturers could pick the engine and even do some tuning. Now, the HP ratings are based on a sample of engines pulled randomly off the assembly line.

So today's HP ratings better reflect the actual rating a consumer will experience in their car.

smartman__007

iTrader: (1)

(I started a redundant thread and figured I'd post my reply there here and have my other thread deleted.)
Same here Gramps. TPI just jumped out at me and I had to read. I looked for specs just now and turned up XR264HR as a part number with a quick google search came up with these specs. http://www.sdpc2000.com/catalog/1976...y-Camshaft.htm

Gramps

iTrader: (1)

ya...there was another thread about the same story, and one of the TGO members contacted superchevy magazine. superchevy said that the cam came in the box and the box had that number on it, but they werent sure if that was the actual cam because they never verified it, the box was opened already and kinda ragged. IIRC anyways.

EDIT: that seems like a weak cam for the 383 anyways.

smartman__007

iTrader: (1)

I'm completely oblivious to Cam specs unless there are comparison numbers with the original nearby. That's still a monster for a SBC. The numbers they got from that would be awesome to see someone run the 1/4 in. If you build this motor I'd love to hear about it. Even if you come within 20 to 30 Lbs-ft I'd say you got it done right. Keep us informed if you build it, always more meaningful to come from someone you can talk to firsthand.

Orr89RocZ

iTrader: (20)

i hope we get an update on this...

Kennerz

I used that cam on my 355, not sure about the HP, but the torque was phenominal. THe mid range pull was impressive- it would flatten out by 5K but this was with ported stok runners. BTW the motor is FS in the classifieds.

Great street motor, now I have a hot cam vortec set up, it has less mid and more top

smartman__007

iTrader: (1)

Not to be a post killer but my opinion stands as Horsepower win's brags, Torque wins drags. Having insane amounts of torque get the vehicle moving. Without torque, it wouldn't even move. Someone please build this motor lol... Not sure on the budget price but I'm sure the big grin you got across your face from the first pull would be worth it.

Guest

I guess thats why 18-wheelers are so fast at the drags.

smartman__007

iTrader: (1)

Wouldn't be the tons and tons of weight they have and double digit forward gears slowing them down would it? If you've got nothing non-sarcastic to say don't say anything.

Grim Reaper

Madmax's point is very valid - torque alone doesn't win drags...you need BOTH HP & TQ. Torque starts you moving but HP gives you the speed. If TQ alone won races, diesels would be the engine of choice for the drags. But they aren't.

There are plenty of quick TPI cars that get into the 12s, but there are very few TPIs in the 11s without a power-adders.

And, AGAIN, they are using the "Gross" method to calculate the TQ/HP. I seriously doubt it makes more than 350RWHP/400RWTQ on a chassis dyno.

smartman__007

iTrader: (1)

Alright Alright, Torque alone won't put you in the winner circle. I'm an . Not to stray too far from topic but isn't HP just a function of TQ?
It sells the magazine to see those big numbers from a SBC but if it would be from a chassis dyno, it would be absolutely INSANE.

Gramps

iTrader: (1)

bah, you just need torque at a higher RPM, the higher the RPM, the more hp your gonna produce (do the math). so my engine that makes 500lbs/ft of torque at 3500RPM would lose to an engine that makes 500lbs/ft at 4000RPM. HP is just a number to brag about.

Grim Reaper

I'm sure it will be a very nice street engine with decent track performance. But it won't be any drag strip terror. Just don't be too surprised that if you take it to a chassis dyno that you discover a whole lot of TQ missing.

laiky

500 lbs/ft at 4000 RPM would mean more HP, so infact, it is something to brag about since you have the faster car. HP is just that, a measure of the power produced. All the torque in the world won't win a race without it producing power. In street trim, torque is handy, since it makes things easier. Gearing is less critical, you get a wider usable powerband, if you have good low speed torque you can get off the line better (to a point). All that is great, but torque doesn't win races, power does.

Imthebriman

iTrader: (1)

It says that the L98 they tested had only a mild cam and long tubes when they got their baseline and it made 327HP...???? So if I get a mild cam and some long tube hookers I can make over 300hp? That is like 80 or so more horses than stock... maybe I read something wrong.

D's89IROCZ

yeah something fishy there . But I do notice a trend in the magazene articles. They always use an aftermarket ECM. In the shootout article I read on here. They made a TPI sing to over 6000 rpm ....which is rediculas. Idon;t think they could have done that with a factory ECM ... Or maybe we just don't know the tuneing tricks to get it that high ???

Imthebriman

iTrader: (1)

I knew something looked wierd when I read it...

Grim Reaper

Yes, they put it on an engine dyno and measured it without any accessories, which is the "Gross Method" that I discussed earlier. Take 25% off the 327 Gross HP reading (to approximate NET HP rating) and you get....245HP...the exact same NET rating from GM.

Which is still only around 200-210 RWHP.

Orr89RocZ

iTrader: (20)

well that first L98 they tested had a magnum 215/215 cam in it...so it gave abit of help on that L98. but its NOT uncommon for stock Corvettes to dyno near 230whp stock

matt_p

Don't use percentile deduction to calculate net hp. When using percentile, the higher the horsepower your engine makes, the more hp it takes to turn your accessories, which is ridiculous. It's as bad as using percentile when calculating drive train loss.

Gramps

iTrader: (1)

WHAT Torque wins races...ask around. and btw Gearing is the MOST important thing that should run hand-in-hand with torque. "it is better to make torque at a higher RPM because you can take advantage of gearing", meaning that if your Peak torque is at say 3500RPM, if you rev to 4G RPM and then shift, your loss in RPM would be close to 3500RPM, so you may lose only 7% of your torque by reving to 4G's, but when you shift, your sitting in the golden number and your at 100% torque. i just had this arguement with another fellow about hp and torque. HP is literally a fake number which used to be measured by actual horses, now its instead converted from torque or from kw/H.


PS: i already stated that but thank you for agreeing with me
----------
ya those aftermarket ECM's are pretty hardcore, and with an elabourate ignition system capable of like 15,000RPM, its no wonder you see results. plus an engine dyno can be controlled way easier than a motor on a chasis dyno and a guy with a screwdriver playin under the hood.

Grim Reaper

The word is "percentage" NOT "percentile".

If it were JUST accessories, I would agree with you. However, when just installing a slightly smaller crank pully is commonly used to save 10-15 HP, you can imagine the difference if you eliminate ALL of the accessories.

But there is MORE to the difference between GROSS & NET than JUST the accessories. Full exhaust versus open headers, open intake versus full air cleaner & ducting, various emission devices like air divertors, EGRs, Air Injectors, etc. Basically GROSS is a "naked" engine with the bare essentials to run while NET means EVERYTHING as installed on the vehicle, but not including the transmission, driveshaft or rear gears and rolling resistance. Do some searching on the Internet to find the complete differences. But the general rule of thumb is NET HP rating is about 75% of GROSS HP rating. And, there is another 10-25% difference between NET HP & Chassiss RWHP (depending on transmission & slippage in the torque convertor and the rest of the power train).

Anyway, if you live in BC, forget about building that engine. The new "green" legislation that is coming out will make any modified engine a thing of the past. Worst, after 2009 you will only be able to buy certain cars in BC. I hope you like the Prius.

Guest

The old torque vs hp arguments.

So tell me, what exactly is torque at a higher rpm? Tell you what, you calculate the torque at a low rpm, and at a high rpm, what are you comparing? You're comparing horsepower numbers. Work over time.

Gramps

iTrader: (1)

lol i acknowledge hp with respect to torque. but if somebody gives me a raw HP rating, im gonna shoot it down because i dont care how much hp your making, i care about how much torque your making. haha obivously this is a never-ending arguement, its like asking "what came first, the chicken or the egg?" (its the egg that came first because it evolved in the egg and became a chicken where as its mother was not a chicken, but a lesser evolved species...case closed).

Grim Reaper

Gramps, it's not a "chicken vs the egg" discussion (unless you chose to make it such). If TQ was the answer, then think of this; at the drag races where they use SBC's - do they build the engine for Torque or for HP? The answer is HP because every good engine builder knows that with "limited displacement" and no power-adder, you can make HP only one way - REV THE SNOT OUT OF IT!

And, all the engines I see at the track go the HP route (ie. rev the snot out of it). If TPI were the answer, you would see that intake on every drag car -but you don't. You do see a lot of "short runner" intakes like the Miniram OR converted carb intakes so they can "rev the snot out of it".

TPI is/was designed for a street car where you tend to want TQ at lower rpms where the engine is typically operating. But it never was (and never will be) designed to be a track terror. That is why guys go out of their way to "siamese" the runners etc - to gain top end HP at a slight cost to TQ.

And they do this because anyone who hangs out at the track for any length of time quickly gets tired being ahead all the way of the other guy for the first 1000 feet, only to get beatened in the end. And that is what HP does to TQ.

As I said earlier, for a nice street engine with descent 1/4 miles times, a big TQ TPI engine is great. But, there are ways of having BOTH TQ & HP. It's called "more displacement" with a short runner intake. A Motown 427 with a Miniram will make tons of TQ and gobs of HP, and hand that engine built by Superchevy it's breakfast, lunch & dinner.

Grim Reaper

I just want to add one thing; many of you would be wise to maybe follow some of Madmax's posts that he's made over the years regarding TPI. Most people who have been with TGO for any length of time know that Madmax and I are NOT buddies. So I am posting this because I truly believe some of you can learn something about TPI from him.

Think about this, when two guys who really don't care too much for each other are saying the same thing - there is probably something to what we are saying.

Again, don't get me wrong. If you WANT to go with the TPI system, there's nothing wrong with that. TPI makes a nice street engine and it can get decent track performance. Just, don't get fooled by those numbers from SuperChevy. Remember this, most of the writers for these car magazines are NOT Mechanical Engineers but English Majors. And they do stories to sell magazines.

But if of you DO build that engine, and DO take it to the track, I will bet most of you will experiment with "siamesed" runners in a short while to find better performance. Then you should check out some of Madmax's posts on that subject.