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Disappointment at the Dyno... LS1 C5 Vette


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So today I drove down to Carolina Automasters and Dyno'ed the new motor. I'd hoped to pick up all the crispness and bottom end I'd lost when installing the new motor. I knew some of it would be tuning, since the program was rich. I'd installed a Z06 MASS meter this morning, with the adapter, in hopes it would help my chances of 400WHP...

 

I got there and Jeff was tuning a 99 Firebird, complete with DS1 Procharger, cage, and about 572HP at the wheels... Nice car indeed. The owner also has a 2nd Gen RX7 with a LT1 in it. Clean car indeed.

 

So my turn on the rollers and we roll out 353HP... :shock: Eh' WTF???

 

Jeff does another couple pulls, cleaning up the fuel maps, and decides something is amiss... So we swap out the NEW meter for the old MASS unit, and the AFRs and mapping stabilizes. We get consistant 360s to 370s at the wheels.

 

Go here to see the dyno sheet... http://photos.yahoo.com/dat74z and click in the vette folder. I scanned in the 5th and 11th runs on the dyno... The good news is the car "feels" fast everywhere now. It launches hard, and pulls like a freight train, kinda like my old motor did... The bad news is the motor is down on power. We think it is the heads and the head work. The 98 model heads had issues, and I assumed (Wrongfully so) that installing bigger valves and extensive port work would clean them up and make them real runners... They may have COST me power... Lesson learned. Jeff tried to relay that to me and the engine builder in the process, but Dave didn't have a ton of experience with LS1 stuff, and I was more inexperienced than Dave.

 

So we're making about 375HP and about 370#ft of torque, and the up shot is I'm getting the power everywhere and the car feels much faster. New heads could easily put me well over the 400HP mark. I'll consider them in the spring. Right now, I'm more focused on spending any additional funds on the Datsun. Another note of interest was that I was knocking down about 27MPG on the way down there, and we saw up to 32pmg on the way back... Amazing. :shock::2thumbs:

 

The build up on this LS1: Forged H-Beam Rods (Heavy and could be robbing some power!), forged Ross pistons, Stock new LS1 Crank (Knife edged) with a new stock LS1 block, Ported 98 model LS1 heads with 2.02/1.57 valves, Thunder racing 224/224 114lsa cam (556 lift), Z06 intake/ injectors, Shander ported Tbody, LGM longtube 1 3/4 headers, and full 3inch exhaust W/ SLP cats. This is a 6 speed car and the rear gearing is 3.42. Redline is set to 6700RPms. I'll not shift it past 6200. Power falls off, so why bother.

 

400HP was the goal and I can't deny my disappointment. However, reality is that I wasn't driving 335HP on a road course to its fullest potential. I'll only swap those heads out if I decide I'm going to sell the car... Dyno sheets and numbers would help sell it. Right now I'm not interested in selling it, but at some point, Well... You know...

 

So there you have it... The cam is worth 40HP and 20-ish Ft.# torque over my previous STOCK LS1 with the same bolt ons.

 

I want to thank Jeff Creech for doing his magic and making this car so fun to drive hard and at speed. The new motor now FEELS soooo much faster and is much more efficient!

Mike

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Yea Mike I would be disapointed too. Like you said, the Darts are on their way, and AFR 205 are expensive, but proven performers like 450 to 470 RWHP. Tony M. has tweaked them and so has Pat G over on LS1Tech. Those guys are also running 90mm TB's with ported Fast Manifolds. Big bucks.

 

You might call TEA and ask Brian if he can rework you heads. He has done that in the past with good success.

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I've still got the heads that came off my 99 block. I could get them worked on... What I anticipate is resolving the head issue, and taking the car, with heads back to north carolina and leaving it for a few days. I'll give Jeff the business to install them, since he'll be retuning the car anyway. He only wants $600 for the install and the retune, so I think that's reasonable. If he was closer, I'd just throw the heads on here, but since it has to go on the trailer to get there anyway, might as well let him fight the PS pump bracket! :lmao:

 

Those 98 heads really surprised me. The story on those is this:

 

I bought the car in early December for $17900. I immediately got Dave Williams and Jeff Creech involved in planning another motor for the car, since Mine had 92K miles on it when I purchased the car. Over the next 9 months I scowered the internet for deals. I found those BRAND NEW heads on ebay for $200. I didn't run the numbers, so that is clearly my fault. I also hadn't heard about the poor performance of earlier LS1 heads until the motor was sitting in my shop, already complete. I took a dial caliper and took some measurements of the intake and exhaust ports on the 98 heads (Already bolted to the block) compared with the 99 heads that were off the old motor and Dave had really opened up the ports on the heads. So I was pretty stoked, thinking "big intake and exhaust runner work, big valves, and a fresh clean up on the bowls!" Wooohooo... Uh no.

 

I don't know. Maybe the intake is restricting it now, but Jeff has been doing this for a long long time and he just shook his head and said "heads".

 

Ugh. Live and learn... I'm still coming out on the good side of bad I suppose. I still have less than $28K total in this car and all its Z06/ performance/ Road race/ stereo/ interior upgrades.

 

Mike

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The dyno has busted my bubble several times. But you know where you're at, and that the tune is right, so you've got a good baseline for the future. The torque curve looks good- I'd take a big flat torque curve over peak hp #'s anytime.

 

AND BTW: You came to Lake Lure? That's rock throwing distance from my place! We shoulda got together and had a cold'un!

 

jt

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JT1, I shoulda... Man, I thought I posted that I was gonna be down in that region... I could live there... GREAT scenery and lots to do... On our list of retirement options for sure!

 

Yea, the dyno busted me hard. My little brother was with me, which made it even more painful, because we both expected bigger numbers... The first run was funny as hell... Shoulda had a picture of my face when I saw 353HP... I was like "all this money on a new, better motor and I come away with 17HP more than my old tired motor with the same bolt ons???" My disposition improved after all the dyno runs were completed and we took it for a test ride. The tune was worth making all the power usable... I just expected much more for a "heads/ Cam" package that is supposed to be a proven combo. :roll:

 

This car is now my daily driver though... With that kinda fuel mileage, I think it might be doing better than the wife's BMW. :lmao:

 

Mike

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Mike,

 

Dude - think about it - 375 HP and 370 lb-ft of torque. Those are great numbers. Maybe not what you expected but look at all the area under the torque curve. I'll bet that car pulls like a freight train! Then over 30mpg highway on top of that. I'm running the same engine getting 311 hp and 25 mpg highway. I've got a long way to go.

 

Along those lines - what is the problem with the '98 head? Valves smaller than the later ones?

Also - what do you think of your cam at this point? Good quality, service? How was pricing? It ooks like the one I'll want eventually for my car. Do oyu remember lift & duration of the stock cam?

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Those heads have been worked on and don't have stock valves in them, which is another pisser... I had 2.02/1.57 valves installed. I don't recall all the information about the 97/98 heads, but your money is better spent on later model units. I've probably got about $800 invested in them, including the springs and retainers.

 

The cam feels great NOW... Before the tune was done, it was very lazy. I gotta tell you guys, and I witness it again first hand yesterday when Jeff called their tech line for an unrelated question, but THUNDER RACING's tech support has been AWESOME from day one.

 

The cam kit and all the parts I bought from thunder are well made, with clear instructions and their service is top shelf. You guys know that I pretty much trash vendors when I don't get reasonable customer support... Well Thunder Racing is at the exact opposite end of the scale... More retailers should be like them... They stand behind the parts they sell, and they sell great parts.

 

That cam is one of their most popular. :2thumbs:

Mike

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  • 3 months later...
Guest speedmon

I know this is an old post, but I thought I would share.

 

Its hard to make power with LS1 heads, unless you shave'em and mod the combustion chamber to emulate the LS6 heads. Stock LS6 heads will make more power than "worked" LS1 heads.

 

The stock Z06 injectors are 28lbs and are over the top of their duty cycle with the engine components you have.......you can see this with a scanner. 30lb SVOs will give you more power.....cheap and easy install.

 

With LS6 heads and 30lbers you'll be easily at 420whp. I've seen your combo make over 450.

 

I'm about to do an LS1 conversion to my Z (what am I thinking). I bought an LS1 engine and tranny, but the 1st thing I'm doing is slapping on LS6 heads, intake, cam and 30 lbs injectors. The LS1 heads MIGHT fetch $200 on ebay if I'm lucky.

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Yup. Mine are even hogged out a bit. I do have new numbers, as the last time we went to the Dyno things had changed a little with my exhaust. After a retune, I picked up 11 more HP and 10#ft. torque.. I'm now at 386/382. As soon as cash flow improves (Next week we're thinking) It'll get a set of Dart aluminum heads and a fast intake. I expect it'll be well over 430WHP with that setup!

 

Mike :2thumbs:

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2.02/1.57 valves isn't everything.

 

My ARE ported LS1 heads flowed 260 with them.

My Patriot/Port Pros LS1 heads flow just over 300 with them.

 

If you need heads, there's an excellent LS1 machinist here, Harold at Port Pros.

 

The PS pump is nothing. **With the correct GM tool** you can have it off and back on in 10 minutes, no exaggeration.

 

Having done the swap before with a Vortech on top of the engine, I'm pretty sure I could do a "regular" LS1 head swap in 1 full day.

 

Aftermarket MAF sensors are looked down on by many LS1 tuners. I'm not the least bit surprised it caused problems. :dunno:

 

Note from MIKE

*Sorry, Thought I hit the Qoute Button and hit the "edit" button on YOUR thread...

 

Multitasking sometimes isn't a good thing!

Mike

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Where did you buy longtubes that fit?

 

This particular motor is in a 99 Chevy Corvette. LG Motorsports makes an excellent fitting 1 3/4" long tube headers! :2thumbs: Won't work on a Datsun, but work great in a C5! :2thumbs:

 

280Z28, Yea, I've done a bunch of research over the alst year. The heads I bought and used we're purchased from a vendor on ebay one month after I bought the Vette back in December 2003. The motor took over 16 months to build over time. Just a combination of me buying and shipping the parts to Dave in Arkansas, and Dave getting time to build the motor. I was in no hurry until this past June when the LS1 in the car blew up.

 

In hind site, I'd not even built what I built. I'd go 402 stroker. But that wasn't an issue back in 2003 when we started.

 

Mike

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MAS, those heads are woefully restrictive on that 402 stroker... You certainly need to upgrade to something much more "appropriate", so just go ahead and pull those off and box them up for me, MMKAY?? :lmao:

 

Hey, can't blame me for trying now, can ya? :-)

 

I'm researched out on heads... Not sure which ones I'll go with... I'm having lots of fun with my 386WHP, but knowing that there is about 30-40 more on tap is killin' me. I'll either go with a set of LS6 take offs that Jeff Creech rubs out for me, a set of the Dart units, or a set off a known combo. My LS1s are so hogged out that the port velocity is pretty much shot. Dave ported the crap out of them... :roll: AT MY SUGGESTION TOO! :twak: I know better... NOW! :lmao:

 

Mike :cool:

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[quote=280Z28

Aftermarket MAF sensors are looked down on by many LS1 tuners. I'm not the least bit surprised it caused problems. :dunno:

 

Actually my MAS was a factory 2004Z06 unit. We don't know what was wrong with it, but it simply wouldn't stabilize at all... Probably a bad electrical component.

 

Mike

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In hind site' date=' I'd not even built what I built. I'd go 402 stroker. But that wasn't an issue back in 2003 when we started.

 

Mike[/quote']

 

Mike, I was telling you more cubes and stroker from day one. In that day, you just had to live with the few pounds a Truck block would add and get aftermarket crank/rods/pistons. Now it's a lot easier.

 

I'll NEVER build another V8 smaller than 400 cubes again. NEVER.

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Guest speedmon

I think he's getting appropriate power from his stuff.....it's all about learning and evolution anyway.......

 

Like check out these guys from SDPC (that scoggin place). Their LS2 402 longblock is making some serious power........LS6 heads (CNC'd) with STOCK valves......better springs though.

 

http://www.ls1tech.com/forums/showthread.php?t=459311

 

They squeezed 582lbs of TQ out of that baby......

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