Marc3.4V6

iTrader: (1)

Maybe my expectations are too high, but no matter what I do I can't seem to get satisfaction from this car. Partly because I've spent entirely too much on it and the motor, partly because I thought being this close to 300 RWHP would feel pretty awesome, but it either doesn't or somehow I'm not getting that much power. I don't race, I just wanted a quick feeling daily driver, nothing crazy. The motor only has 25k miles on it and it's given me a bit of trouble and it feels like the power has only gotten worse. When I first got my pcm tune from madz28, it would chirp second easily, often without me trying to. Now it just feels sluggish most of the time. I replaced plugs, wires, and every sensor I could think of when a headgasket blew at 12k miles. I was going to get some new wires but I doubt that'd help. I'm still paying off the motor so I couldn't even think about selling it although sometimes I wish I could. I still need to get it painted, it's been primer for too long and I just moved to a new place so major upgrades like a new tranny are almost completely out of the question. My dad's Z71 1500 Chevy Avalanche w/ 3.73's feel quicker in many areas than my Z28. I am lighter and had the same HP/tq rating plus or minus 10 hp/tq when stock, but now have at least 60 more RWHP, but his truck feels strong. It gets up to speed using less rpms, plus it is only at 2k rpms at 75 mph. It doesn't have the same top speed so on the highway the z28 is a bit quicker.

So, I'm going to give this car one last chance to get to a place where it feels like it's where it should be. Unfortunately a likely culprit could be the transmission, the most expensive. Likely because it seems like everything else is in order and when I got my transmission serviced they said it looked like it had never been serviced before, that's 145k miles without service. Yet it was still able to put down 290 rwhp and 320 tq 2 years ago, so maybe not. So let's start with things I could afford.

Gears - would 3.73 gears make a difference if I already have 3.23 gears?

Tune up - Plugs/wires could have fouled for unknown reasons. For my level, do I need to run a colder plug, are stock injectors enough?

Tuning - I already have a madZ tune, but perhaps dyno tuning could tweak more power out of it and change a rich or lean condition, or other problem?

Cam only swap - The cam in it isn't spectacular, maybe a custom grind emissions cam with more torque that starts a little lower would put a smile back on my face? I make 320 tq at 4169 rpms and 290 rwhp at 5180 rpms.

This is my last ditch effort before I give up on making this car quick as it should be and just driving it thinking of it as a slow car until I can get something I want, I'm tired of hating it. What do you think is the best next step?

WS Sick

Drive the v6 around for a while then drive the v8 one. problem solved

camar0corey

iTrader: (22)

I don't see a stall listed in your mods. If the transmission is good I would do a stall and 3.73s.
I guess what really sucks is you are stuck in Commiefornia. Get a pre 1972 car or whatever and go crazy? Is that still the law out there, pre 74 or 72 and you don't have to worry about the smog *****?

Marc3.4V6

iTrader: (1)

yea so far it's still the law, who knows if they'll try to smog those too. I'm scared to put a stall in a tranny with that much on the clock, but hell maybe I will. The v6 was totaled and sold.

Puck

iTrader: (17)

A4 LT1 without a stall is slow, period. IMO nothing will give as much bang for buck to an auto as nitrous - longtubes are the only mod that even comes close.

Throw in a decent stall and your car will be a whole new animal, even though it may dyno less. If that's still not enough, 3.73s will give you more pep off the line as well.

riceburnerZ28

iTrader: (20)

Get yourself a stall and/or gears maybe even a dynotune should help.

WhitePhoenix99

iTrader: (12)

What is a "mild" crane cam? You are making what a bolt-on car would make. I would get a dyno tune and see how much power you are leaving on the table.

323steel36

A4s arent slow. Especially mines isnt. Go with 3.73s youl feel it on the launch and highway.

97pontta

iTrader: (10)

If you think your noticing a power decrease I would check to make sure the engine is 100%. I know it only has 25K miles but do a leak down test to be sure. What condition are the O2's in? If they had gotten fouled at any point they can cause issues as well. You said you did a full tune up which is a great start. Things like burnt wires, fouled plugs, a dirty MAF, vacuum leak, bad O2's can be had to detect and really reduce power and throttle response.

If everything checks out good I would suggest a stall. When I installed my CC305 cam I left the stock stall in as well. The car was a TURD off the line. I got a 3400 stall and dropped .7 off my 1/4 mile times and picked up 3 MPH, that was with me still running the stock 3.23 gears. I noticed a bigger gain with the stall then when I swapped to 3.90 gears but the gears are an improvement as well.

bowtienut

iTrader: (1)

Get the idea of a cam change completely out of your head.
That would REALLY complicate sorting out what's wrong with the car!
Almost any cam that would physically fit in a SBC/LT1 should perform better than what you're seeing. Basics first!

Puck

iTrader: (17)

Without a stall, yes they are .

Trick450r

iTrader: (7)

X2, I dont believe i've seen any Cam in an lt1 with bolt ons making less than 300 rwhp. Even through an auto.

My vote goes to a stall and a dyno tune, I think you have pre-existing issues.

Marc3.4V6

iTrader: (1)

The cam is barely bigger than stock. When the motor was built, I didn't know very much and I told them I didn't want to have to tune it, so they picked this cam for me

http://www.summitracing.com/parts/CR...4&autoview=sku

whytryz28

iTrader: (28)

This, I had stall, gears and tune, I was walking bolt on 05 style GTs all day and hanging with C6 vettes.

bowtienut

iTrader: (1)

That's an excellent cam for where you are with the car right now.
Even if those ported heads are no more capable than stock, you're leaving at least 30 hp on the table right now. Any idea what kind of valvesprings you're running? If the springs are good, fuel supply is good, and ignition is good, you're just a dyno tune away from 325 rwhp.
BUT...........you still need a good TC and gears to make the car quick.

myk

iTrader: (4)

So the car isn't tuned? Correct me if I'm wrong but you just can't throw a cam in these cars and expect to not tune it. Well you can of course, but you should expect to have a poorly running/under-performing car which is what I think we have here. I think a tune alone would probably wake the car up a little. Stall and gears will make it a different machine altogether, although tune it after the stall and gears obviously...

bowtienut

iTrader: (1)

His original post says a mail order tune. Not sufficient, IMO.

Marc3.4V6

iTrader: (1)

Thanks for all the great replies, guys. Yes, it has a mail order tune. My valesprings are actually really good, .600 max lift. IIRC. My paperwork says these are it. http://www.summitracing.com/parts/CRN-11309-1/ , still on stock rockers but they sound like a sewing machine anyways.

Today it was actually running pretty decent the whole day until I started heading home and it was sluggish again. It's very inconsistent. It was pulling pretty good even under 2k rpms earlier. Also, in the morning when it's cold sometimes my trans slams into drive and reverse and shifts late for the amount of throttle I give. After warming up it shifts normally. I just had a trans leak fixed that is still leaking slightly. I brought it in because it wouldn't shift sometimes, turned out it was 3 qts low, despite me never seeing any fluid before. So I think putting a stall in there, even with my trans cooler may be a bad idea.

Looks like a gears and a dyno tune is in my near future. The shop that built my motor used to have prices on their website but now don't, when they did they listed $800 for dyno tuning gm vehicles. How's that? There's only one other place I know of I'd have to call them too for pricing, though I probably won't be doing it for a while. Gears followed by a quick mail tune for them will be sooner, my manager is good friends with the owner of a gear shop, hopefully I can get it installed fairly cheap. I'll be looking for motive or AAM gears.

This forum has helped me a lot since I got this car, and you guys are very encouraging, thanks.

Ralls

iTrader: (32)

$800 for a dyno tune sounds too much. Prices are going to vary throughout the country, but I live in an expensive area and I paid like $400 or maybe $500 for a tune for only bolt ons. My last dyno tune cost me $700 and that was tuning a completely new turbocharged 383 stroker and speed density tuned.

I also agree, a QUALITY torque converter with higher ratio gears will make the car feel much faster.

camar0corey

iTrader: (22)

$800 is a lot! I paid $400 for a dynotune for cam/boltons. Check in the CA section to see who all can dynotune LT1s in your area. Hell if they built you the motor they could have at least cut you a deal for a dyno tune.