4.8 Build NEW TO FORCED INDUCTION
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4.8 Build NEW TO FORCED INDUCTION Thanks for comments. First off I'm building my first forced induction engine. I have about 50 naturally aspirated engines under my belt. I have been given a FREE 4.8 engine. All tolerances were very very close so I put it back together with new bearings and New flat top hypereutectic pistons. Went back with the stock dimple rods and crank. I'm trashing the 862 heads because of the valve size. I was going to install 243 or 799 heads but NOW I have decided to boost it. I think I'm going with the 317 heads to help with the CR. Is this a right decision. Also have not purchased the cam yet. Had decided on a 212/218 @ .50 with a LSA of 114 because it will be a daily driver Gears are 3.73 Can't wait to see how it works out. Not sure how much power it will make but I'm hoping for a good increase. All suggestions are appreciated and highly regarded. As I said I'm new to this.
The 243 heads seems to be the head of choice for almost all cathedral boost builds these days. Maybe 317’s on a bigger 4.0 bore where the compression will be a little higher.
I agree with JoeNova tho the valve size is probably not going to have much affect on a small bore boost engine unless you were really had a max effort setup. So stock heads or 243’s would be my choice. I would not lower the compression any more with 317’s. Especially on a daily driver
I agree with JoeNova tho the valve size is probably not going to have much affect on a small bore boost engine unless you were really had a max effort setup. So stock heads or 243’s would be my choice. I would not lower the compression any more with 317’s. Especially on a daily driver
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Well that's a good question. I really don't know. I'm just now diving into this turbo thing and I'm learning. I was thinking about a 76mm
T3/T4 T04E V-BAND Turbocharger Turbo .63 A/R .5A/R Internal Wastegate Yes I do realize this is a cheap Ebay turbo that may or may not last but its my first go around.
I don't want too much lag in the spool either on this short stroke engine but again I don't really know what to get
T3/T4 T04E V-BAND Turbocharger Turbo .63 A/R .5A/R Internal Wastegate Yes I do realize this is a cheap Ebay turbo that may or may not last but its my first go around.
I don't want too much lag in the spool either on this short stroke engine but again I don't really know what to get
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Turbo Sizing Hi Joey, the size choice of a Turbocharge (1,2,x) is based on requested Horse Power.
Get the Compressor Map then ALL here can help.
I would fit a "late" Z06 camshaft for an average cost of $100.00.
We "benched" 1291 @ 22.lbs on a LS-393 with this camshaft.
Your A/R should be .96 with .81 as the smallest choice. (Twins)
As STATED by Joe, SAVE money, use your OE heads.
I would install better valves, possibly an EV-8 Exhaust of larger size.
I would drop the seats for a C/C increase, use a "dish" intake EV-4 or 6.
I would install PSI 1511ML Springs.
I would install CHE's.
I would install a new Oil Pump, 2010 Camare OR the OEM larger rotor pump needed for "twins"
I would install a single Timing Set, Avon Gear.
These items I can supply ?
Lance
Get the Compressor Map then ALL here can help.
I would fit a "late" Z06 camshaft for an average cost of $100.00.
We "benched" 1291 @ 22.lbs on a LS-393 with this camshaft.
Your A/R should be .96 with .81 as the smallest choice. (Twins)
As STATED by Joe, SAVE money, use your OE heads.
I would install better valves, possibly an EV-8 Exhaust of larger size.
I would drop the seats for a C/C increase, use a "dish" intake EV-4 or 6.
I would install PSI 1511ML Springs.
I would install CHE's.
I would install a new Oil Pump, 2010 Camare OR the OEM larger rotor pump needed for "twins"
I would install a single Timing Set, Avon Gear.
These items I can supply ?
Lance
Joined: Mar 2007
Posts: 1,145
Likes: 50
From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
Why are people so adverse to compression in a boosted engine? Weird.
Run the small valve heads, bowl blend them if it makes you feel better. Nothing wrong with two smaller twins.
Run the small valve heads, bowl blend them if it makes you feel better. Nothing wrong with two smaller twins.
Hi Joey, the size choice of a Turbocharge (1,2,x) is based on requested Horse Power.
Get the Compressor Map then ALL here can help.
I would fit a "late" Z06 camshaft for an average cost of $100.00.
We "benched" 1291 @ 22.lbs on a LS-393 with this camshaft.
Your A/R should be .96 with .81 as the smallest choice. (Twins)
As STATED by Joe, SAVE money, use your OE heads.
I would install better valves, possibly an EV-8 Exhaust of larger size.
I would drop the seats for a C/C increase, use a "dish" intake EV-4 or 6.
I would install PSI 1511ML Springs.
I would install CHE's.
I would install a new Oil Pump, 2010 Camare OR the OEM larger rotor pump needed for "twins"
I would install a single Timing Set, Avon Gear.
These items I can supply ?
Lance
Get the Compressor Map then ALL here can help.
I would fit a "late" Z06 camshaft for an average cost of $100.00.
We "benched" 1291 @ 22.lbs on a LS-393 with this camshaft.
Your A/R should be .96 with .81 as the smallest choice. (Twins)
As STATED by Joe, SAVE money, use your OE heads.
I would install better valves, possibly an EV-8 Exhaust of larger size.
I would drop the seats for a C/C increase, use a "dish" intake EV-4 or 6.
I would install PSI 1511ML Springs.
I would install CHE's.
I would install a new Oil Pump, 2010 Camare OR the OEM larger rotor pump needed for "twins"
I would install a single Timing Set, Avon Gear.
These items I can supply ?
Lance
Thread Starter
Registered User
Joined: Feb 2018
Posts: 7
Likes: 0
thanks for all the input. I have decided to use the 862 heads. Going to start rebuilding them tonight. Have all new parts on the shelf. I can now put that $ elsewhere in the build. Still have not decided on which turbo(s) to go with. Twins sound like they would spool up faster because of the size but I really am not sure about room. I was thinking maybe a procharger instead but they are proud of those things and I'm not sure how quick those things spool up. Another thought...the reason I'm so concerned with the spool time is this is going to be a street car and not an all out drag car. That being said, since I haven't purchased an intake yet (engine didn't come with one) I am contemplating on a whipple style charger. They are proud of those also but I have found a few that is not so bad.
Decisions Decisions Oh one thing I haven't mentioned is the HP goal. I hope to make 600 out of this 4.8 . Like I said it's going to be a daily driver running on pump gas. gears will be 3.73 with probably a 700R also thinking about Brian Tooley Stage 2 4.8 cam
Decisions Decisions Oh one thing I haven't mentioned is the HP goal. I hope to make 600 out of this 4.8 . Like I said it's going to be a daily driver running on pump gas. gears will be 3.73 with probably a 700R also thinking about Brian Tooley Stage 2 4.8 cam
thanks for all the input. I have decided to use the 862 heads. Going to start rebuilding them tonight. Have all new parts on the shelf. I can now put that $ elsewhere in the build. Still have not decided on which turbo(s) to go with. Twins sound like they would spool up faster because of the size but I really am not sure about room. I was thinking maybe a procharger instead but they are proud of those things and I'm not sure how quick those things spool up. Another thought...the reason I'm so concerned with the spool time is this is going to be a street car and not an all out drag car. That being said, since I haven't purchased an intake yet (engine didn't come with one) I am contemplating on a whipple style charger. They are proud of those also but I have found a few that is not so bad.
Decisions Decisions Oh one thing I haven't mentioned is the HP goal. I hope to make 600 out of this 4.8 . Like I said it's going to be a daily driver running on pump gas. gears will be 3.73 with probably a 700R also thinking about Brian Tooley Stage 2 4.8 cam
Decisions Decisions Oh one thing I haven't mentioned is the HP goal. I hope to make 600 out of this 4.8 . Like I said it's going to be a daily driver running on pump gas. gears will be 3.73 with probably a 700R also thinking about Brian Tooley Stage 2 4.8 cam
2nd call or go to the vsracing site, the billet 69mm gt45 seems it would be good for your goals. However the reputation of the 7875 and now the billet 7875 is hard to ignore. I have not had both turbos but feel the 7875 would spool quicker than the smaller wheel gt45. I know the gt45 is physically bigger.
A BTR or lil John or Tick turbo cam will make a world of difference, but like as already been stated stock GM cams have met your goals many times. Even some people run the stock truck cams
Ive been curious about the billet version but havent seen anybody try it. I think for the price the cast 7875 is hard to beat