Stock TPI base.
Safety Car
Joined: Dec 1999
Posts: 4,691
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From: Framingham MA
Re: Stock TPI base. (devilfish)
Can you port the stock tpi base? Is the tpis big mouth just a stock ported tpi base? Or is it more to this then just porting.
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Stock TPI base. (devilfish)
the Bigmouth has much bigger ports and allows some more porting
its based on the TPI manifold, but is a totally different casting
and it flows alot better than the stock ported
its based on the TPI manifold, but is a totally different casting
and it flows alot better than the stock ported
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Stock TPI base. (devilfish)
About the best you can do for a stock base in siameese the adjacent runners.
The big mouth is totally different, and the rear runners interfere with the distributor mounting, so it has to be machined for the stock distributor to still fit, or you have to use a small base distributor.
Either way, the big mouth is totally different in physical size.
The big mouth is totally different, and the rear runners interfere with the distributor mounting, so it has to be machined for the stock distributor to still fit, or you have to use a small base distributor.
Either way, the big mouth is totally different in physical size.
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
Re: Stock TPI base. (vader86)
and it flows alot better than the stock ported
Team Owner
Joined: Sep 2001
Posts: 62,126
Likes: 1,727
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Stock TPI base. (dgoodhue)
Do you know which base they tested it against? the Accel, TPiS, edelbrock?
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Re: Stock TPI base. (vader86)
http://iroc.fbody.com/intake.html
Here is some info that may or not or may not be accurate and is justa link I found one day, I swear! , (see the THINK BEFORE YOU POST THREAD)
Here is some info that may or not or may not be accurate and is justa link I found one day, I swear! , (see the THINK BEFORE YOU POST THREAD)
Safety Car
Joined: Dec 1999
Posts: 4,691
Likes: 1
From: Framingham MA
Re: Stock TPI base. (vader86)
I honestly don't remember, but I want to say it was an edlebrock. I am pretty sure it was on the thirdgen, I can't find the exact thread though.
I did find this though, which seems to have a good porting advise.
<A HREF="http://www.thirdgen.org/techbb2/showthread.php?s=&threadid=43923&highlig ht=stock+ported+intake+flow%2A" TARGET="_blank">http://www.thirdgen.org/techbb2/showthread.php?s=&threadid=43923&highlig ht=stock+ported+intake+flow%2A</a>
about half way down
Where the ported intake flow 255cfm vs stock 220cfm, which is close to teh number of
http://iroc.fbody.com/intake.html
The intake numbers of 222cfm stock & 251cfm Accell
I did find this though, which seems to have a good porting advise.
<A HREF="http://www.thirdgen.org/techbb2/showthread.php?s=&threadid=43923&highlig ht=stock+ported+intake+flow%2A" TARGET="_blank">http://www.thirdgen.org/techbb2/showthread.php?s=&threadid=43923&highlig ht=stock+ported+intake+flow%2A</a>
about half way down
Where the ported intake flow 255cfm vs stock 220cfm, which is close to teh number of
http://iroc.fbody.com/intake.html
The intake numbers of 222cfm stock & 251cfm Accell
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Le Mans Master
Joined: Apr 2000
Posts: 6,341
Likes: 1
From: Shelton CT
Re: Stock TPI base. (dgoodhue)
If you port the lower intake be careful..
if you siamese the runners on the lowe rintake, factor in, that goign too deep
will totally mess your engine's charctersitics up.
Example : Siamese 3" deep and you might gain about 1K rpm higher breathing, but since your cam is designed for UNDEE that, you just sacrificed who knows how much power on the low end. It ahs to be a nicely thouht out balance. I was gonan do this on my car, as I have the whole intake, ported and siamesed with SLP runners, but I woudl have only gone 1" deep to add about 300rpms or so more breathing and not mess with the car's cam. (I don't want to mess with the engine's original design, see how fast I can get her)..
It is a pita to do though..Not looking forward to it..
I was thinking of offering this service to corvette owners, but doubt I could
get enough business to make it worthwhile..
if you siamese the runners on the lowe rintake, factor in, that goign too deep
will totally mess your engine's charctersitics up.
Example : Siamese 3" deep and you might gain about 1K rpm higher breathing, but since your cam is designed for UNDEE that, you just sacrificed who knows how much power on the low end. It ahs to be a nicely thouht out balance. I was gonan do this on my car, as I have the whole intake, ported and siamesed with SLP runners, but I woudl have only gone 1" deep to add about 300rpms or so more breathing and not mess with the car's cam. (I don't want to mess with the engine's original design, see how fast I can get her)..
It is a pita to do though..Not looking forward to it..
I was thinking of offering this service to corvette owners, but doubt I could
get enough business to make it worthwhile..
Racer
Joined: Nov 2002
Posts: 471
Likes: 0
From: Queens NY
Re: Stock TPI base. (MrNuke)
This is probably a naive question, but isn't it only necessary to break the stock 225 cfm per port if your cylinder head can take that much?
I have an intake off my old IROC I was thinking of porting but I'm not totally sure how i'm going to go about it yet, does anyone have pictures of ported stock manifolds? :confused:
I have an intake off my old IROC I was thinking of porting but I'm not totally sure how i'm going to go about it yet, does anyone have pictures of ported stock manifolds? :confused:
Team Owner
Joined: Aug 2000
Posts: 42,934
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From: Sydney, Australia
CI 6-7-8-9-10 Veteran
St. Jude Donor '07-'08-'09-'10-'11-'12-'13-'14-'15-'16-‘17, '22
Re: Stock TPI base. (CarAteMyMoney)
Sorry, I really don't intend to hijack this thread (I know it is against the rules) but I have to say I love your username, CarAteMyMoney. :D
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Stock TPI base. (CarAteMyMoney)
This is probably a naive question, but isn't it only necessary to break the stock 225 cfm per port if your cylinder head can take that much?
It is not the 225 cfm flow rate that is the problem here with the stock TPI...it is the air flow resonance due to the geometry of the runners that impedes airflow at high rpms.
Ironically, it is the same effect that increases low RPM power by aiding air flow at 1000-2000RPM, allowing greater than 100% Volumetric efficiency in the cylinders without supercharging.
By cutting a channel between the adjacent runners, you alter the resonance characteristics of the manifold ( or the "TUNE" of the "Tuned Port" ). This is what gets you the resulting increase in high RPM air flow, not just making the port bigger. Technically, I guess you could say it's decreasing the impedance to high RPM air flow...instead of increasing the airflow directly.
[Modified by BBA, 1:00 AM 12/6/2002]
Melting Slicks
Joined: Apr 2002
Posts: 3,019
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From: down that one road next to that big tree
Re: Stock TPI base. (BBA)
*stock flow at .500 is actually 193cfm, the 225 cfm you stated & i'm taking a ballpark guess here came from my old post on 113 casting flow?* if it didn't i appologize but it's funny my home ported 113 castings flow 225cfm@.500 lift, it took some work to get that however. manley race flo necked valves, a 3 angle job, some bowl porting and short turn radius work along with a small increase in runner volume & removing casting flaws. this is a pretty good post with some pretty decent advice. if you can buy a accel or TPIS base i highly suggest you do so, the casting is larger and SAVES YOU SO MUCH TIME trying to port a gm one, and i mean a LOT of time, like over 10hrs on a port bench to really cut a stock one open and finish it up. it's nuts really espessialy when accel bases are $389 and TPIS is what? like 475? they are basically the same by the way so i'd get the accel one. it also allows the siamesed runner or super ram top to go on at a later date without worrying if the base flows enough.
Team Owner
Joined: Dec 2000
Posts: 21,094
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From: Phila., PA burbs
Re: Stock TPI base. (BBA)
The big mouth is totally different, and the rear runners interfere with the distributor mounting, so it has to be machined for the stock distributor to still fit, or you have to use a small base distributor.
Team Owner
Joined: Aug 2000
Posts: 42,934
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From: Sydney, Australia
CI 6-7-8-9-10 Veteran
St. Jude Donor '07-'08-'09-'10-'11-'12-'13-'14-'15-'16-‘17, '22
Re: Stock TPI base. (TA)
The only "mod" I had to do after installing my ACCEL base was bending the EGR electrical plug bracket that bolts to the rear of the thermostat housing upward to fit by hand. No other fit issues whatsoever.
Here are the pics I have on my homepage, both bases are as cast with no porting:
ACCEL base at top: http://temp.corvetteforum.net/c3/red..._sizes_sml.jpg
OEM at top, ACCEL at bottom: http://temp.corvetteforum.net/c3/red..._sizes_sml.jpg
I took measurements when I did the install and there is so much less material in the OEM base that you would have to port it to within an inch of it's life to reach the port size of the stock,unported ACCEL base.
[Modified by Red 90 L98 Coupe, 1:03 AM 12/8/2002]
Here are the pics I have on my homepage, both bases are as cast with no porting:
ACCEL base at top: http://temp.corvetteforum.net/c3/red..._sizes_sml.jpg
OEM at top, ACCEL at bottom: http://temp.corvetteforum.net/c3/red..._sizes_sml.jpg
I took measurements when I did the install and there is so much less material in the OEM base that you would have to port it to within an inch of it's life to reach the port size of the stock,unported ACCEL base.
[Modified by Red 90 L98 Coupe, 1:03 AM 12/8/2002]
