Need a new motor

[dan291000]

http://www.chevy350engines.com/
http://www.crateenginedepot.com/store/category.aspx?SID=1&Category_ID=273&Page=2
http://www.chevy-350-engines.com/chevy-engine-250.html
http://www.precisionengine.com/rebuilt-engines/chevy-gmc-crate-engines/index.html
http://cgi.ebay.com/ebaymotors/ws/e...r_id=145936675500&ua=?*F?&itemid=310246158592

 

[retorq]

[/COLOR]OK, whats the difference between these 2 motors, one is for 8500 GVW and the other for under 8500 GVW...does the one for the heavier weight have more tq? The lack of specs drives me crazy!

http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=225981

http://paceperformance.com/index.asp?PageAction=VIEWPROD&ProdID=225980

One is a 2 bolt main block, the other is a 4 bolt main.

Ours should have 2 bolt mains.

The heavier duty trucks (over 8500lbs) should have the 4 bolt mains ...

---------- Post added at 07:32 PM ---------- Previous post was at 07:29 PM ----------

Is this for your DD?
I'm asking because I have been inquiering about a new motor (somewhere down the line) and found a forged 355 for $1500, its a short block which is the only set back. You could freshen up your heads and bolt them on along with your manifold and be ready to go.
I'll have to try to find the link/e-mail, its been a while.

If your heads and intake are good a short block is fine. I would have no problem with grabbing that and dropping some cash into getting the heads gone over.

 

[atis]

Thanks for the links. Wouldnt you want to get the 4 bolt if upgrading the motor? For $100 more it seems like the ideal thing to do.

 

[retorq]

Thanks for the links. Wouldnt you want to get the 4 bolt if upgrading the motor? For $100 more it seems like the ideal thing to do.

Yes.

 

[Jaycenk]

You don't need 4 bolts. Not unless you are towing one hell of a trailer and beating on it with a 4,5 or 6 speed manual and making some power. You can run 2 bolts on anything street driven under 500hp and not seeing above 6500. Tons of F-body guys run camaro 2 bolt main blocks with mild stroker motors. I have an lt1 with 2 bolts and a stroker making close to 500 ftlbs of torque and it spins under 6500 in my 97 camaro. If your going for full on race or offroad type driving fine get a 4bolt but on the street even slightly wild on the street you do not need it in these trucks unless you are 2500 series or over.

As for engines it's one of those deals... you better find a way to come up with the money now to do the bottom end right the first time other wise you will be blowing the money. Best bet is to have a set of heads worked so they flow better and change the cam. You can still get great fuel milage and a boost in power on a 350 or 355 just have a tune done on the pcm. Other wise throw the replacement engine in there and use the 255hp and 325 ftlbs or what ever it was for 2000 modle year. Heads make the power so even if you go stock now you can upgrade the cam and heads down the road. Stock these engines have decent pistons in them so you can change compression by milling heads or thiner head gaskets. go with a full roller valve train and higher ratio rocker and blamo the thing can make 400 400. on the POS Stock vortec intake and fuel system. may need injectors with heads and cam depending on what you get.

 

[atis]

any tricks to improving the mpg on the 383? I figure if I am going to save for her might as well add a few items to the list that will help with the mpg.

My Hoe is all stock...right down to the exhaust.

 

[Jaycenk]

Thats a question for an engine builder. Proper head and cam combo is the key. The 383 that GMPP sells builds big low end to midrange torque. It also only spins to 5k rpms. building an engine with a full roller valve train is a good start but cam and head work will really determine the rest. 383 is not going to be easy on fuel. The vortec 350 was really quite good on fuel. doind a 350 or 355 will save you in the fuel department. More cubes means more fuel. Your final drive and tire sizes as well as weight are the biggest contibuting factors to fuel. The idea is to have an engine and truck with the best power to weight ratio taking into acount the engines minimum fuel requirments. If your going to try and make 400hp in a truck that weighs 5000+lbs your going to consume fuel doing it. The nice thing about old body styles is they don't weigh as much as the newer modles that have come out since. Like others have said a simple 6.0 and 4l80E or a 5.3 and 4l60e swap may net you the over all power and fuel efficiancy you are looking for. A mild cam swap and some head work as well as a full roller valvetrain on a 6.0 could easily net you 400+ crank and roughly 320 to 350 rwhp. I have looked at the GMPP383 and thought about it but for what I see 5.3 compleate engines with PCM/Harness/ and 4l60e transmissions on ebay for (under 3000 if not closer to 1500) I am going to be looking in that direction when I do mine. A little more work but it has been done and some of the guys who have done it have posted how to's. The newer gen3 small blocks have more efficiant ignition, fuel induction and cylider heads stock than stock vortec engines. and with a little work on one of the gen 3's you will have the power and millage for about the same price as having yours machined, stroked and heads worked + tune. Maybe a tad more. but still under 5k for a compleate STOCK gen3 swap over. and that includes opening it up and checking bearings and changing seals plus all the little stuff to convert. Fuel efficiancy and strokers really don't go together in a truck. Lighter cars like Camaro's and mustangs can get away with it. Power to weight ratio in thier favor. I'd say a 350 or 355 is going to be the best bet for fuel efficiancy and you can still make power. just not as much torque as a 383.

 

[atis]

My concern is that the Tahoe Limited is supposedly "tweaked" for a little more power then the standard vortec 350...but I am not sure where they did the tweaking so that raises concerns with a new 350 crate motor. I was thinking electric fan and a better exhaust will help but not to the extent that I am hoping. I was getting 18 mph highway and 8-9mpg highway while towing. The stroker hopefully will net me 12 mpg towing...that would make me happy.

 

[Jaycenk]

You are going to have to do alot of transmission work in order to allow the 4l60e to hold that much toque in 4th gear. You would have to go with something like a preformabuilt level 2 and I doubt the PCM would still allow it to hold any kind of lock up if you even run it in lock up. I run a stroker like I said in my 97 with a 4l60e and it wont stay in lockup that long. Even if your running it unlocked in 4th 4th gear in a 4l60e isn't know for holding the torque that well. The amount of pressure created on the apply servo with that kind of power you may only see 10mpg's out of a stroker due to the increase in cubes and the fact that it wont be able to run in lock up unless you are running 373 gears and still don't think the pcm will allow it. You would have to be making 550+ftlbs of torque at 2300 in order to keep that kind of fuel millage. My 98 Tahoe has the standard vortec all stock and 323 gears with NO tow haul mode so When I towed my 21 foot boat down to the keys I had to run in 3rd. I have 160k On the trans so I did not want to have problems since I cant stop the converter from locking up so I ran in 3rd all the time. I got 10 to 11mpg towing My boat and tandem axle that weighs about 3000lbs + I had 2 weeks worth of supplys cloths and half a tool box + 2 aduls and 1 child. I figure I was hauling a total of about 3800 to 4100lbs of extra weight. The truck was right in the edge of my torque curve at 2200 to 2400rpms while doing 60 to 65. That was through the tropical storm comming up Florida at the time. With my 2007 tundra double cab with the 4.7 last year I only got around 9mpg no mater what I did. at the same rpms. The tundra out weighs the Tahoe by about 1000lbs. Ideally you should start talking to engine builders and get their ideas on how to build the best fuel eco out of what you have, and what your needs are. Any builder who has been around has ended up building one to do exactly what you are looking for and can give you real world numbers what any type of engine you can build for that thing can do in your truck with the weight of the truck and trailer taken into consideration. You and I can sit here all year long and speculate what heads what cam what tune will do what, but most engine builders worth a damn are gonna have 10x better idea of what real world numbers are going to be.

 

[atis]

Jaycen, I understand, I have to run in 3rd as well when I tow as well. If not I bounce in and out of 4th gear on the stock motor with the trailer. Not fun. the 9 mpg was in 3rd all the way to southern GA frm NC. Choices, chioces... no fun at all. I want the best of both worlds but can only have one or the other!