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hey guys I'm wanting to buy a 5.7l vortec and rebuild it to put in my 98 c1500. I'd really like to go with a 383 rotating ***. I'm wondering how much hp and tq will the stock heads and intake manifold support. I've seen a spacer (not tb spacer) that goes between the two intake pieces that allows 31% more volume to the runners. The spacer along with some bigger injectors and 80mm tb, would that provide enough for a 383? Would something like a street/strip cam and gm's "fast burn" heads be to much for the intake to handle? Sorry for all the questions at once.
31% more volume to the runners. The spacer along with some bigger injectors and 80mm tb,
There are np bigger injectors for the stock intake I know of. Unless you swap to the vortec marine intake or the ram jet style. Not to mention that seems like a lot of money for the stock intake that has alot of restrictions toflow any way.
I would do the 383 and intake swap to the marine style intake since you will need a new harness anyway going from the 4.3 to 350.
There are post on this do alittle searching.
'73 Scout II 4x4 Vortec 5.3 4L65E np241
'01 VW Beetle TDI-50mpg or better!
'56 Belair 4 door hardtop*next LSx project* 5.3/4l60/3.08's (looking for 25+mpg!)
You can install the 383 with Vortec heads on it. The HT383 that was available from GM uses Vortec L31 heads, the GMPP 383 shortblock and the Ramjet 350 roller cam with specs of 196°/206° duration at 0.050" lift and 0.431"/0.451" of lift on a 109° LSA produces 340 hp@4500 and 435 lb/ft of torque at 4000rpm.
The stock 19 lb/hr poppet injectors are good for around 330 rwhp or 400 crank hp.
A 1998 GMC with a 383, Vortec iron L31 heads, GM LT4 Hotcam with 218°/228° duration at 0.050" lift and 0.525"/0.525" lift with 1.6:1 rockers with a 112° LSA and the stock intake and injection made 328 rwhp and ran a 14.0 in the 1/4 mile.
A head swap would also be nice.
The iron small port Bowtie heads will help over the crappy stock L31 heads. These heads will bolt directly in place of the stockers. Then you can turn around and sell your Vortec L31 heads.
Here they are with 175cc intake ports and 65cc exhaust ports http://www.sdpc2000.com/catalog/3129...inder-Head.htm
Your selection of heads will be dictated on what you do with your truck. If you tow all the time then i would go with the smaller sized intake ports to keep low rpm torque available for towing. It sucks to tow heavy objects havinmg to downshift into 2nd or 3rd and rev the **** out of your engine, just ask the 4.8, 5.3 guys. if you use the truck as more of a playtoy, then the larger intake port heads can really wake up an engine at higher rpm.
the stock intake/ injector(poppet) assembly on your Vortec 350 limits powerto around 400 crank or 330 rwhp due to the restrictive intake and small 19 lb/hr injectors whuch cannot be replaced with larger pieces like other EFI systems, like LS1, LT1 and TPI. If you want to get some major power go with the Ramjet 350 intake manifold or the Marine intake like I am using. Both of these intake flow more than the stock piece and allow the use of more conventional injectors of which higher flow ratings are available.
here is the Marine intake, notice the injectors, fuel rails and fuel pressure regulator on te outside of the intake, the stock L31 Vortec 350 intake has all this stuff on the iNSIDE of the intake restricting flow. http://www.sfatek.com/images/efi.jpg
here are some pics of the stock intake compared to the marine manifold(scroll down) as well as pics of the stock "poppets" spider and the MPFI GM Conversion "spider", both are 19 lb/hr rated. http://www.performancetrucks.net/for...d.php?t=356743
This GM Performance Parts 383 has 4 bolt mains, a forged crank and forged PM rods(stronger than the older Pink rods they replaced) and will accept any roller cam and any heads you want to use(make sure the head matches your intake manifold) it has cast hypereutectic pistons which are stronger than plain cast aluminum but not as strong, but much quieter when cold than forged pistons. This 383 can be had in longblock(block heads, lower end) or shorblock(no heads). it is a ver strong unit and is the basis for the 340 hp (with Vortec heads)HT383 and the 425 hp ZZ383 with Fastburn heads.
To install these 383's in your truck, you need to remove the crank positions sensor reluctor ring from your old crank and slide it on the new crank, as well as using a new plastic 8 bolt front timig cover.
Here is the ZZ383 that makes 425 hp and 460 lb/ft of torque. These have been installed in L31 Vortec 350 trucks, PCM tuning is a must. Full hp may not be realized because of the intake and injector insufficiences, it will still put you in your seat though, for sure. The ZZ383 uses this roller cam:222°/230° duration at 0.050" lift and 0.509"/0.528" of lift on 112° LSA
here is the shortblock version, just add your Vortec heads and you have the HT 383, not made anymore due to GM not producing Vortec L31 heads any more you stock L31 Vortec 350 roller cam would work but I would seriously look into the LT4 Hotcam or the Ramjet 350/HT383 cam with 196/206 degrees of duration at 0.050" lift and 0.431/.451" lift using 1.5:1 rockers with a 109 LSA. http://www.sdpc2000.com/catalog/514/...e-Assembly.htm
The Fastburn aluminum Vortecs, the 170 OR 200 ETECS, Large or small port BOWTIE IRON Vortec heads, stock L31 Vortec heads, Racing Heads service's vortec 350 heads, and AFR's 180cc intake port Vortec aluminum 74cc chamber heads will ALL fit your intake manifold and can be used on your truck for some good power gains on a 383 or from stock power to increased power on your 350 engine.
Here is a couple engines that you should look at
4 bolt L31 replacemnt(this was the engine used in teh Vortec 1 ton trucks due to its 4 bolt mains, your Vortec 350 will have 2 bolt mains0 http://www.sdpc2000.com/catalog/514/...e-Assembly.htm
The stock vortec heads have a limiting exhaust port configuration. This why ANY non-stock Vortec head will give you gains, just how big of gains depends on what heads you use. You can spend thousands on boltons, I wish I would have just gotten a set of head and a cam from the beginning. The stroker was out of my budget, but is a nice addition.
Longtube headers from Hooker pn 2462 with 1 5/8 primaries an 2 1/2" collectors will fit your truck and will allow you to eliminate the not so high flow stock headpipes(pipes from manifolds to cats) which measure 1 7/8's OD. These headers are available in stainless 2462 2HKR, steel ceramic coated 2462 1HKR and painted steel 2462 HKR, prices are $570, $324 and $180 respectivley. http://store.summitracing.com/defaul...=egnsearch.asp
I used aftermarket dual 2 1/2" cats connected to the headers via dual 2 1/2" stainless headpipes. Headers, exhaust and a PCm tune dropped my 1/4 mile times by 3/4 of second and the truck drove completly different, very very nice improvement. And this was with a completely stock L31 Vortec 350 just like yours.
I welded in some O2 sensor bungs in each headpipe, so i didnt disturb the ceramic coating. If you wish to retain EGR then you will need to add an EGR supply fitting to the drives side header, any competent exhaust shop can do this for you.
If you ever plan on forced induction in the future, I suggest you step up to the 1 3/4" primary 3" collector Hooker Super Competition header p/n http://store.summitracing.com/defaul...=egnsearch.asp these HOK 2806 1HKR are ceramic coated for $728 and the HOK 2806 HKR which are painted steel for $419US.
If you are building a stroker, you may want to consider offset grinding the rod journals to the small rod size which will net you a stroke of 3.875" and with an overbore of 0.040 or 0.060"(cant remember) will rsult in a smallblock 396 cubic inch engine. Nice ring to it IMO.
Just an idea to be a bit different.
The Fastburn heads have 210 cc intake ports and have D shaped exhaust ports, large tube headers are required to cover the exhaust ports properly. For this reason I would probably gp with the large port BOWTIE Vortec heads as they have a more conventional exhaust design. The Fastburn heads use the LT1/LT4 exhaust port design. Hedman makes a D-shaped port header, not sure if they are made for the trucks though.
Let me know what kind of emmissions testing you have in your area and a max. money budget, what you use teh Tahoe for and what you expect and then we can help you pick a package much better. When I do this for poeple, I feel like a kid in a candy store.
Ohh, that spacer you are talking about. Since the injectors, fuel pressure regulator, injector wiring, supply hoses and all the other injection crap is on the INSIDE of the intake, I can see that spacer helping airflow inside of the plenums. They make some bold statements about flow increases, I think gains are probable, to what extent I dont know. The money you put into that intake spacer, will only leave you about $500 or so left on a Marine Intake. I got mine from a friend in the US for $750 US complete with injectors that were flow tested. If you want I can put you in contact with him. He sells a complete package that includes colour coded wires to match the stock truck injector loom wires, injector plug connectors. He also sent me 2 t-body gaskets for the 454 and 496 bigblocks as the Vortec 350 uses a sela in the intake, but teh marine intake doesnt have this seal, so the bigblock throttle body gaskets fit 100%.The only thing I needed was to buy some fuel line hose and fittings along with intake manifold gaskets. I did the whole swap, including shipping on an 80 lb package from teh US, plus border charges for under $1000 US total. The MArine Intake parts if you bought them new would be over $3000US. Going used is the way to go. I saw a marine intake go for $900 on ebay.
I was the 2nd person of our Marine Intake project in North America to install the intake. I am using the stock Marine injectors which flow 28 lb/hr at my 60 psi of fuel pressure. I have noticed much better higher rpm power, I am running a stock longblock with boltons and headers.
Here is a thread all about the Marine intake conversion. A Ramjet intake manifold can slo be used and on a NA engine will probably be worth a few hp over the Marine piece. The intek runners of teh MArine intake are slightly larger than the stock L31 truck intake. The MArine intake was used on Marine 350 and 383 engines with ratings up to 330 hp.
Here is another pic of the Marine intake http://www.sfatek.com/images/efi.jpg I am using teh L31 stock truck T-body and the nly tuning change I HAD to make was to change the injector flow rating. Obviuosly more power can be made when a proper dyno tune is done. But its not like the truck wont run without tuning.
You already have a 75mm throttlebody, I suggest taking your stock t-body and removing the EGR diffuser plate that looks like a 1/2 moon shaped piece on the back of the throttle body. I would only use a larger throttle body with a supercharger. The 75 mm piece will for sure feed a 383 just fine. I think yiou could even use a 78 mm LS1 t-body, but the increase in T-body size is not worth the tuning headaches, unless you plan on getting a dyno tune.
Post back with any questions, we'll try to get them answered.
Sorry about the book, I love Vortec stuff.
I would go with a ZZ4!That is what I am doin and also stepping up to bowtie vortec haeds here pretty soon along with a ramjet.Now tuning will be no biggie seeing I have my own software and can tune it on my own.
Like Hog said the stock poppet valves are not good for but about 330rwhp and I am only about 30rwhp from it,so with the heads and the 383 it will be a must to step up to a ramjet.I like the marine but I like the ranlets better and that is what i am goin with.I already have some Manley stainless vales ready to go in the heads,just need to order the heads and that will be real soon!
Custom mail order tuning for your specific application!! EFILive Autocal is also available!!
Custom Tuning available for 96-14 GM trucks and SUV's
wow, thanks for all the info hog. this has really pointed me in the right direction. i had to read your book a couple of times for it to soak in but I really thank you for helping me and taking the time to explain it. It's only left me with one problem now... 383 or 396 lol
Indigo Blue 1998 C1500 4.3L Stock
1999 T/A A4 Stock 3.23's
Best Pass 2.19 60' 9.07 1/8 @ 80.99 Track Elevation 3010'
Mods: FRA; Custimized 40 Series Flowmaster; Cut out; AIR!; SLP lid; Ported TB; Bump Stop Mod; Ported MAF
Next Mod: Probably Never