Engine and Transmission Tech

tips, technology, tools and techniques related to vehicle driveline components

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mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: October 20, 2023 01:53PM

85-87 single plane intake:
s-l1600 (16).jpg


ag1234
Arthur Gertz

(66 posts)

Registered:
03/29/2023 08:26PM

Main British Car:


Re: 4.5/4.9 Cadillac V8
Posted by: ag1234
Date: October 21, 2023 05:34AM

Perhaps this helps explain the "weird" center intake ports on each side ? Runner length vs velocity, with a single plane ? I want to install an Eaton M112. I suspect a modded single plane will work better, Jim ?


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: October 21, 2023 05:06PM

This guy used a M90:

[www.fiero.nl]

Another:

[www.fiero.nl]



Edited 1 time(s). Last edit at 10/21/2023 06:29PM by mgb260.


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: October 22, 2023 11:35AM

The single plane small throttle bores for the early 4.5 are a carryover from the 4.1. Probably same intake. Need to be bored bigger. The dual plane on later 4.5 and 4.9 are much larger.



Edited 1 time(s). Last edit at 10/22/2023 12:54PM by mgb260.


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: October 22, 2023 11:49AM

Art, The Allante lower intake would be best for a Supercharger. Will only work with 90 4.5 PFI or 4.9 heads.
s-l1600 (19).jpg



Edited 1 time(s). Last edit at 10/22/2023 12:41PM by mgb260.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6469 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 4.5/4.9 Cadillac V8
Posted by: BlownMGB-V8
Date: October 22, 2023 11:53AM

It would be pretty easy to make a blower intake for that.

When they redesigned the lifter mount did they run the individual lifter bolts into the head?

Jim


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: October 22, 2023 12:40PM

Jim, They made a couple of dog legs in the valve cover sealing area due to injector locations. If a person wanted to go carb or TBI the injector holes would have to be plugged. 88-90 4.5 are TBI and 91-95 4.9 are PFI. 88-90 4.5 and 91-95 4.9 all use the ribbed reinforced block. The only carryover is the 4.5 used the old style oil pump that should be swapped to the 4.9 pump. The 4.5 has shorter stroke and longer rods than the 4.9. Everyone should avoid the 4.1 motor except a few parts like the oil pan or valve covers.



Edited 1 time(s). Last edit at 10/22/2023 10:51PM by mgb260.



mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: October 22, 2023 12:53PM

Jim, that reminds me. The lifter angle of the older motors with flat tappets and removing Zinc from oil caused early wear to the cam lobes. The gasket materials and Dexcool anti-freeze were issues. Also the early blocks had porosity and cracking issues. The small 4. 1 was also stressed pushing the weight of a heavy car. As far as stock net HP rating the 4.9 with 200HP and 275TQ look pretty good compared to 302 Ford or 307 Chevy that were not over 180HP and 250TQ. The 4.5 Allante was rated 220HP due to the better intake manifold.



Edited 1 time(s). Last edit at 10/23/2023 10:27PM by mgb260.


ag1234
Arthur Gertz

(66 posts)

Registered:
03/29/2023 08:26PM

Main British Car:


Re: 4.5/4.9 Cadillac V8, big mains, small rods
Posted by: ag1234
Date: November 20, 2023 09:22PM

I see their logic. Big mains give more rigidity and crank pin overlap.Small rods reduces I loads and makes a smaller rod ark. Plus it has hyd. rolled fillets on RJ's
Onward, Art.


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 4.5/4.9 Cadillac V8, big mains, small rods
Posted by: MGBV8
Date: November 21, 2023 10:47AM

The 1968-1971 Chevy 307 was rated 200HP/300TQ with a 2 bbl carb.


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: November 21, 2023 12:07PM

Carl, I meant after 72 when they went to "Net" HP. The Caddy if around pre-smog would still be higher than the Ford or Chevy!


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 4.5/4.9 Cadillac V8
Posted by: MGBV8
Date: November 22, 2023 10:08AM

Got it.

Not completely sold on this gross vs net HP business.


Scott68B
Scott Costanzo
Columbus, Ohio
(562 posts)

Registered:
10/25/2007 11:30AM

Main British Car:
1968 MGB GM 5.3 LS4 V8

authors avatar
Re: 4.5/4.9 Cadillac V8
Posted by: Scott68B
Date: November 22, 2023 08:18PM

Quote:
Not completely sold on this gross vs net HP business.

[youtu.be]


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6469 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 4.5/4.9 Cadillac V8
Posted by: BlownMGB-V8
Date: November 23, 2023 07:57AM

He was wrong about one thing, the fan drag he showed was probably pretty close. At room temperature it would be fully engaged and only disengages as the temp of the air from the radiator goes up.

Running the fan inside a shroud and with resistance to airflow from the radiator might increase the load some, I don't know how much.

But to me the takeaway from this was that between the fan, headers, and intake system that we run on the MGB we probably don't have that much difference between the gross and net HP since we are basically just dragging along the water pump and alternator.

Jim


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: November 23, 2023 10:29AM

Power steering Hydraulic pump and AC compressor was also figured in the Net HP ratings. 74-84 had more smog control, ran hotter and leaner. Also had retarded timing, so were pretty gutless.



MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: 4.5/4.9 Cadillac V8
Posted by: MGBV8
Date: November 23, 2023 10:30AM

My 215 is a 1963 JN block 11:1 comp. rated 200 HP that was rebuild back all standard. Rear wheel dyno'd at 162 HP. In this case, gross & net horsepower are very close to the same.

The '67-'69 Chevy 302 real world HP was considerably higher than the advertised gross HP. :)


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: January 06, 2024 04:30PM

88-89 4.5 has smaller Rover sized valves. 90-91 Allante 4.5 has the same larger valves as 91-95 4.9. The Allante 4.5 has longer connecting rods and the shorter 4.9 pistons. This may be helpful for those that mix and match parts.


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: February 24, 2024 03:43PM

Hypothetical 4.9 build. Ported heads, cam specs similar to Ford 5.0 HO roller. 600cfm Holley carb, headers.
4.9_page-0001.jpg


mgb260
Jim Nichols
Sequim,WA
(2462 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 4.5/4.9 Cadillac V8
Posted by: mgb260
Date: February 24, 2024 08:45PM

Looks a little better spread out to show the nice torque curve.

4.9 2_page-0001.jpg
4.9_page-0001 (1).jpg



Edited 1 time(s). Last edit at 02/24/2024 08:47PM by mgb260.


ag1234
Arthur Gertz

(66 posts)

Registered:
03/29/2023 08:26PM

Main British Car:


Re: 4.5/4.9 Cadillac V8
Posted by: ag1234
Date: February 25, 2024 07:14PM

Is there a flow bench report for ported 4.9L.heads ? Using an M90 blower on a 4,9L. sounds out-matched. Any temp rise and boost data ?
Thanks, Art
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