Hey all,

If I go with the 305 stroker do I have to change out my knock sensor and chip ?

This is what I have assumed so far -- a speed density system doesn't care about more air (eg: cubic inches) but is very sensitive to more fuel (eg: increased camshaft intake duration).

So by going with a stroker motor from 305 to 331 (or 334 ?) inches the ECM should adjust right ? I figured no matter what I decided engine-wise (stroker, 350, etc) I'd keep the same factory cam (203/208/.429/.431) and avoid any immediate issues with the chip. Is that correct ? Have any of you cube builders on SD engines had to reprogram it or it wouldn't run situations ?

Also, I am not clear how the knock sensor is effected however have been told that an increase in cubes will cause it to operate differently. Does anyone know if I'd have to change the knock sensor on a stroker 305 ?

thxs in advance,
RP.

 

Hey palric... I would swap to MASS AIR setup.. but thats my opinion, and no one agrees with it anyway.

I don't think a new knock sensor is needed, just some bigger fuel injectors and some custom chip programming

 

IF you decide to swap to MAF(kinda backwards)..Ill trade for whatever you need for whatever I need to swap to SD..

Daz

 

ahhhh.. the argument of SD vs MASS AIR....

 

I would tend to agree with Nathan here about switching to MAF. Of course if you switch to MAF you would have to swap the ECM as well and therefore good time to look into a chip, but this would be optional. But if you don't want to switch and want to stay with you SD setup, then based on what I've been told you should start saving for a custom chip for sure. Or even invest in a ECM from a 350?!?

As far as the knock sensor goes, I don't have a clue...I would leave it as is and once everything is said and done, hook up some diagnostics software to it and watch your knock counts.

 

nate you should spend some time on the prom burning board and see what they have to say about MAF. every one of them will tell you to change to SD. for some one that can burn their own chips it is the way to go. seeing as how most of use can not burn our own chips the MAF is better. Untill your mods out flow the MAF. However i dont think converting would be the way to go.

to convert back would also require a different wire harness also.

as a general rule, a displacement change of more than 10% will need a chip done. but from all the work you are looking a doing it would be best to get one.
the best place to get the info would be the prom board. Be warned they will tell you that you need a chip even with no mods.

 

I am not going to argue at which is better. If you have the equipment to custom burn proms... then go SD.. if not.. I'd stay or go to Mass Air. My preference is Mass Air, since GM reverted back to it in the new cars.

 

palric,

i dont know much about TPI and i am no expert when it comes to cars, but why stay with the stock cam? i know that if you get a performance cam you will need a custom chip, but it sounds like everyone else is saying you need a new chip anyway. if you increase you displacement, your already mild cam will act even milder and you wont be making near as much power as you could be. if you go 350 or more cubic inches a more aggressive cam would help make lots of power, especially with the head work you are planning and some headers and a low restriction exhuast. you will be able to go with a real nice aggresive cam too seeing as you have a 5 speed, unlike those of us stuck with stock torgue converters on our automatics and no money to afford either a better converter or manual tranny swap (ie. me). anyway, i just think you could make alot of power by swapping in a better cam while you are building you new motor. when i got a new cam put in my LG4, it really woke up that engine. just my 2 cents.

 

Hey how are you doing -- are you going to the GB weekend ?

If I was carbureted I might change out cams as there are alot better profiles available in non-roller profiles than the stock setup in the LG4. The carb'ed 305 can easily goto 214 degrees on the intake and the usual .500 lift with 1.6 rockers. Pretty common solution that I have seen work really well on a number of occasions.

The Speed Density (SD) LB9 however is a different animal. It is exceptionally sensitive to changes in fuel ratios because it has a very limited response curve according to it's ECM programming. This means that if you change the cam to a more usefull profile eg214/224 and .480/.480 are common) you will push yourself into some serious calibration issues in order to fully take advantage of the new cam's capability (MAF setups are known to be much friendlier to fuel enrichment mods). I tried a cam swap years ago on an SD system, went to a 217/225 and .480/.505 cam and spent $$$ and months trying to get a chip to work with the new setup. It never did work quite right however chip mod'ing has improved alot since then.

One thing I did learn was the SD system takes the old adage that the engine is nothing but an air pump -- to an extreme. Increasing cubic inches in an SD system can require NO chip mods, in other words it is optional depending on other co-existant engine mods.

This is important to me because it is a litmus test for driveability, in other words will the car still run reasonably well with the stock chip still in place after ALL mods ? My car has to be a great daily driver after all mods have been done. Having heavily mod'd an SD 305 once before I can tell you that loss of driveability is a major issue that can steal all the joy of having the car.

The stock cam is a reasonably aggressive profile. In fact the GM marine master and ramjet engine cams have between 198 and 208 degrees duration on the intake yet make 330 and 385 hp with their 'small' cams. This is why I am staying with the stock cam. As far as I am concerned the only problem with my engine is it is short on cubes -- for a mild street performer (eg: around 300hp) and could use some 'system' improvements like head work and exhaust headers, etc.

BTW: I had an '85 IROC with a stick and LG4 wayyyy back when. It REALLY woke up with some simple mods, eg: intake, cam and exhuast (I loved that car unfortunately it was stolen and destroyed). Have you done any of these mods yet ? Also, is the T-5 swap very painful for your car ?

thx,
RP.

 

i am well, how about yourself? i plan on going to the Gbend for that weekend. it really is the place to be on the long weekend and its only 25 minutes from my house.

After reading your reply i can understand why you are hestitant to change your cam. if you are goign to all the expensive and effort to build a goodo performing motor, the last thing you want is to not have it work right or not be drivable. plus its your project and you should do it the way you want it.

yeah i have done/had done intake, cam, headers, catback exhuast. plus i removed all the emissions stuff, including the cat. i made myself a dual snorkel air cleaner and put a K&N in it. the cam and stuff really made my car alot more fun to drive. in terms of the T-5 swap. that would be real painful on my bank account. plus i have never done anything near as complicated as that and i am sure i dont have all the tools necessary or the necessary skill. i am still planning on putting on that dual exhaust system i asked you guys about awhile ago. the weather and school and lack of funds has stalled that a bit. but today is my last exam and tomorrow i start work, so as soon as i can afford a couple hooker aerochambers, that project is a go.

 

Look forward to meeting you and checking out your car at GB. A T-5 swap would have to be carefully planned but jeez it is worth it for the LG4 setup. Well maybe sometime in the future you will have time to look into it ? Wait till I do my T-56 swap -- I'll have all kinds of T-5 stuff lying around and no place to store it...

I remember your dual exhaust debate on the board. Us with all the reasons why NOT to do it (typical) and you go do it anyway (typical hot-rodder, ha, ha). That is what makes this fun. Of course after you have the duals installed ALL OF US will be checking it out secretly figuring "can I do that too ?!?!?!?".... I loved the sound of my 2nd 3rdgen car, an '88 Formula, it had headers to mandrel tubing to high-flow everything all in 3inch inside diameter piping. I used to rev that car just because I loved the sound of it. I never, ever got tired of the exhaust note on that car. I hope you find the same with your duals -- it ought to be a killer setup.

adious,
RP.

 

palric,

i sure hope the dual setup i am lookign at running works out. i desperately want to get rid of the crappy, restrictive factoyry y-pipe setup and get the car sounding nice and loud...i mean real loud. loud is good. anyway when you do you T-56 swap you might have to store you T-5 stuff at my place and i can store some crisp bills in your wallet. anyway i just finished my last exam, so i am going to have a nap before the big raptors game and big canadiens games tonight.

later

 

Rich...you are a funny guy! All that knowledge you just provided us with above and you had to ask us about the chip and knock sensor?!?

 

I have discovered that you don't know what you don't know until you find out what you didn't know. So I like to ask questions because there are alot of very experienced car guys on the board who might save me tons of grief by preventing me from jumping into mods without proper homework (this is how the car becomes a black hole for $$$$).

The knock sensor thing is something I wanted to work out well in advance. I am looking at installing a stroker, a 350, or a 400sb (will make up my mind later this summer) and regardless of choice I don't want to get derailed by ECM issues. Low probability that it is, I wanted to find out for sure in advance.

I was checking out the specs on a 400sbc that would make about 300hp and 350lbs torque on a super mild cam profile. Killer eh ? Wonder what my gas bill would be ? Ouch.

How is your car running ? Is it on the road yet ? I am in B.C. this week and the weather is hot, hot, hot and the roads are full of everyone's summer rides. Pretty cool.

RP.