plenum style intake lean rear cylinders a problem ?
Thread Starter
Instructor
Joined: Jul 2007
Posts: 117
Likes: 0
plenum style intake lean rear cylinders a problem ?
hi there ,
i have heard along the lines that plenum intake styles like mini ram,super ram ,stealth ram e.c.t that have long plenum box can tend to give the rear cyliders a lean type of tune!
as the front first cylinders grab the fresh /cold air first and then the rear cylinders get whats left of it !
if so how can you over come this problem please?
is there any way of fixing this problem at all such as a custom tune/chip or some thing else may be ?
would rear cylinders that are running leaner than the front ones be bad as far as all round performance is concerned ?
what do you guys think about this,is it really much of a problem ?
hope to hear soon some facts/comments on this please.
when you see those 8 throttle body seperate style intakes that each have there own t/b they are all getting the same amount of fresh air arent they so there fore it is a much better tune/run.
thanks
tyson
i have heard along the lines that plenum intake styles like mini ram,super ram ,stealth ram e.c.t that have long plenum box can tend to give the rear cyliders a lean type of tune!
as the front first cylinders grab the fresh /cold air first and then the rear cylinders get whats left of it !
if so how can you over come this problem please?
is there any way of fixing this problem at all such as a custom tune/chip or some thing else may be ?
would rear cylinders that are running leaner than the front ones be bad as far as all round performance is concerned ?
what do you guys think about this,is it really much of a problem ?
hope to hear soon some facts/comments on this please.
when you see those 8 throttle body seperate style intakes that each have there own t/b they are all getting the same amount of fresh air arent they so there fore it is a much better tune/run.
thanks
tyson
Last edited by prism_kiter; Aug 1, 2007 at 07:12 AM.
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
I think you mean to say less air to rear cylinders would be a richer not leaner condition. When I have injectors CC'd to check flow rate, I will usually put the lower flow rate ones in the rear cylinders since they do get robbed of some air. You will find a lot of injector sets, if checked, will have an acceptable 1 to 2 percent variation tolerance in flow unless you want to spend extra money on additional injectors and have them checked to get a matched set.
Rick
Rick
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Change the firing order, which would require a cam ground as such. #5 and 7 steal air from eachother at high rpm but IMO I doubt youd experience a SOTP difference it you did . Lots of money spent for ???
Last edited by cv67; Aug 1, 2007 at 10:12 AM.
Pro
Joined: Mar 2005
Posts: 746
Likes: 0
From: Rochester PA
firing order change
cuisinartvette,
What is the deal with changing the firing order of # 5 and #7? I have heard it produces more HP. How could that be? Why hasn't Chevy done it if it works? Thanks.
Rich K
What is the deal with changing the firing order of # 5 and #7? I have heard it produces more HP. How could that be? Why hasn't Chevy done it if it works? Thanks.
Rich K
Pro
Joined: Jun 2007
Posts: 577
Likes: 0
From: the best car on earth ,vettes are best
Tech Contributor
Joined: Jun 2004
Posts: 20,857
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I'm in complete agreement with you on the poor cost/benefit ratio of this change.
Tech Contributor
Joined: Jun 2004
Posts: 20,857
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Safety Car
Joined: May 2002
Posts: 4,659
Likes: 82
From: Toronto ontario
I've been doing my own tuning on My 388 LT4 using the gen 7 dfi. Reading the plugs showed me clearly that the front was running lean, the middles normal and the rear rich. I know you're thinking lean but as someone pointed out less air and the same amount of fuel would equal a richer mixture.
I changed my plugs regularly on my 93 LT1 when it was stock with bolt ons. All the plugs read the same. My new 388 was spinning near 8k rpm and the plugs showed this condition every time. From my best guess, this becomes a problem only when you're rpming the motor beyond 6500 rpms.
I changed my plugs regularly on my 93 LT1 when it was stock with bolt ons. All the plugs read the same. My new 388 was spinning near 8k rpm and the plugs showed this condition every time. From my best guess, this becomes a problem only when you're rpming the motor beyond 6500 rpms.
Drifting
Joined: Oct 2006
Posts: 1,554
Likes: 13
From: Romeoville IL
I've seen dyno sheets where the rearranged firing order works... I think it was on a single plane manifold. I'm not sold on the idea for TPI or LT-1 style fuel injection.
