TRExp

Spitfire & GT6 Forum

1500 engine performance mods

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

clshore Carter Shore
Beverly Hills, Florida, USA   USA
Yup, you got me, cams are iron:

Running an iron journal in aluminum = OK
Running an iron journal in cast iron case = really, really, not OK.

In normal proper use, the journals don't touch the bearing surface, as they
are hydrodynamic, the oil film supports and seperates the surfaces.

But at startup there is contact, and also when oil pressure is low (idle RPM), or loads are high (max RPM).

Ask a tribologist why iron-iron is bad (galling).

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Dickie B Avatar
Dickie B Dickie Brewer
Clover, South Carolina, USA   USA
1973 Triumph Spitfire MkIV "Rose"
1982 Chevrolet Corvette "Buddy"
1991 BMW 850i "Rocket"
2005 Nissan Frontier V6 "NIZMO"
Nice to hear somebody knows what hydrodynamic lubrication is! Very nice!

AJ6mod6 Avatar
AJ6mod6 Gareth T
Disabled Account, Antarctica   ATA
1989 Jaguar XJ40 "Animal2"
In reply to # 863606 by clshore
In normal proper use, the journals don't touch the bearing surface, as they
are hydrodynamic, the oil film supports and seperates the surfaces.

Ask a tribologist why iron-iron is bad (galling).

EXCEPT when the 2 surfaces are 90 degrees to each other in a load bearing condition....

Cast iron piston rings>cast iron bores (GOOD) but in reality the rings are NOT in fact flat.
The actualgas tight fit is in reality convex, leading to a non seizable condition....

Cast iron followers are iron/iron but in fact the CAM lobe is NOT flat but has a slight convexivity of a few minutes of a degree, again leading to a non seizable condition...also they are BOTH chill cast so close to 55 (RK C) each.

One of the FEW condition which is bad, is untreated native nodular cast iron against same cast iron in the same load bearing plane.
It relies on the self lubricating effect of the carbon nodules/micro-crevices to hold enough oil to prevent seizure....a perfectly seizable condition when you decrease film strength and up the temperature!

In a lathe bed, not a problem.
In the ovalised point contact of a cam journal with all the load pointing downwards in the same plane under intense vibration, a totally different story!

The introduction of Nitriding (ferric nitride) or localised induction hardening can delay galling & seizure and but not for ever.
By it's nature you can't introduce it inside the cam journal except by fitting a different (soft) alloy metal.

You can't defy gravity, but you can fly or glide a little longer....if you excuse the pun (!)**

NB:-I have managed to get a GT6 to develop near 180bhp without using soft alloy cam bearings, but the cam was tufftrided + it uses light single valve springs.
It does go to 7300rpm without failure several years already...

Here's an interesting little article on the problems introduced by heat & vibration in such an environment..

remember.....

"Current certification requirements of the FAA, EASA and Transport Canada require that the aircraft must be able to continue safe flight for at least 30 minutes after the crew has detected lubrication system failure or loss of lubrication. This is sometimes referred to as “the 30-minute run-dry requirement.”

http://www.ainonline.com/aviation-news/aviation-international-news/2013-01-01/main-gearbox-remains-helicopters-achilles-heel



Edited 3 time(s). Last edit at 2013-01-22 10:49 AM by AJ6mod6.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
90632D Avatar
90632D Fox Trapper
Various, USA   USA
All those iron piston rings sliding up and down in iron cylinder bores....

The residual oil on the surfaces seems to do just fine on startup, for both piston rings and camshafts.

As for running camshafts in aluminum being OK, I've seen a whole lot of failures there. It works, as it does in iron, but both have limitations, and neither are as good as a fully enclosed babbit bearing, but both work reasonably well for production engines.

AJ6mod6 Avatar
AJ6mod6 Gareth T
Disabled Account, Antarctica   ATA
1989 Jaguar XJ40 "Animal2"
In reply to # 863631 by 90632D As for running camshafts in aluminum being OK, I've seen a whole lot of failures there.

You are completely wrong here.
The replaceable bearings used in the Jaguar XK engine were a total waste of money for 40 years, as there was NEVER any wear there.

On the 12 cylinder or 24 valve engine I have never EVER seen a failure or wear of any sort and that is at stratospheric mileages.
Since 1973 Jaguar has been making 100s of 1000s of engines without them having a single failure here.

Their camshaft manufacturer may have something to do with it.
Lydney never made anything for the cut price - cheapo end of the market like Triumph or MG, only quality companies like Cosworth and Jaguar.

If you see the horrible failures on Maserati or Stag V8 bear in mind the cam loads are never symettric and and the firing order leads to all kinds of nightmares all over the valve train, not just in the cam journals....

Hankers1500 Nigel Makin
Felixstowe, Suffolk, UK   GBR
Just joined the website having read this thread and noted a wealth of experience here, thanks.

I had a 1500 many years ago (30+) and improved it with some basic spanner and screwdriver skills. Changed the inlet manifold to replace the SUs with Stromberg carbs (opinion at that time was that with diaphragms they suited the Spit better than the SUs), fitted a tuned exhaust manifold, electronic ignition (very basic in those days), an electric radiator fan. After colour tuning it, it improved the 70-100mph performance to a level that you would expect from a production 1500 small car in those days. I was well pleased. Eventually it went the way small cars go when families come! I now want to get another one and have a similar ambition to the one stated by this threads initiators, Jeff and Brittany.

"I'd like to rebuild and upgrade for greater performance and reliability, to take advantage of modern engine components, the years of tuning and development on this engine since the 70's, and the wealth of engine building experience that has amassed since the engines were introduced....(Not for racing, just to bring them into the 21st Century and to get my little Midget screaming down the road)"

Can this be done without a major engine rebuild, as I did in the past? Admittedly the cars were not so old then! And the average car performance standards were somewhat lower! If so, what spanner-based mods can pep up a 1500 in this day and age?

Nige.

clshore Carter Shore
Beverly Hills, Florida, USA   USA
Probably the bast 'bang for buck' is fit the Euro dual SU intake, and exhaust.
Change the cam if you are up for it.
Replace/modify the stock dizzy to get a performance oriented advance curve.
Increase the compression ratio somewhat (10:1 is reasonable), by skimming the head.

Convince Gareth to sell you one of his cylinder heads.

Carter

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Hankers1500 Nigel Makin
Felixstowe, Suffolk, UK   GBR
Hi Carter, I'm likely to start with the Euro dual SU intake over here; the other stuff I'll bear in mind for starters, thanks, Nige.

Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
I'm building a nice street 1500 engine now, 9.0 to 1 pistons, a new APT street performance cam, I got the 1300 cam and I used the 1300 cam bearing in the 1500 block. The owner has done some mild porting, I'm going to do a little more porting. Nothing drastic, but should be good improvement, over stock.



Hap Waldrop
Acme Speed Shop
864-370-3000
www.acmespeedshop.com
Engines, Rebuild Kits and More.


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - Alloy wheels for British Sport Cars,and others
Hankers1500 Nigel Makin
Felixstowe, Suffolk, UK   GBR
Hi Hap, interesting, how many horses do you expect to get from the engine you are building?

Hi Paul G, I've just read your page Triumph Spitfire Performance Enhancements (March 2013 edition) and found the answers to most of my questions. Thanks for a very good and clear write up, it has given me much food for thought.

Nige.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 905133 by Hankers1500 Hi Hap, interesting, how many horses do you expect to get from the engine you are building?



I have no idea, this list of mods, more compression ratio, better cam, head porting normally makes for about 15-20% increase over stock.



Hap Waldrop
Acme Speed Shop
864-370-3000
www.acmespeedshop.com
Engines, Rebuild Kits and More.


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - Alloy wheels for British Sport Cars,and others
clshore Carter Shore
Beverly Hills, Florida, USA   USA
In reply to # 905091 by Hankers1500 Hi Carter, I'm likely to start with the Euro dual SU intake over here; the other stuff I'll bear in mind for starters, thanks, Nige.

Yah, I had noted your UK location, then promptly forgot when I penned my posting.

Johnmcmd John A
Lakewood, WA, USA   USA
9:1 flat top pistons; mill the head .020 to clean it up as part of valve job; cleaned up intake/exhaust ports to eliminate mismatch between header, gasket and head; DVG Weber carb and manifold; mild cam regrind to pump up midrange. Made a big difference but perhaps the most important was re-jetting the Weber which was running very lean. Weber main jets are cheap so I ordered a set and went up 20 from 140 to 160 primary and 135 to 155 secondary. Much smoother transition from primary to secondary and a lot more power. Runs fine on regular gas but packs a punch over stock. However, power has to come from somewhere and thus gas mileage suffered a bit....maybe just me putting my foot in it more often. Weber DVG primary is about 30% smaller than the stock Stromberg but when the secondary opens up the combined size is nearly 46% larger. Power comes on at about 3000 rpm and the carb really roars.

Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
I missed the mention of roller rocker arms before, here's my take on them, and lords knows I don tons of R&D testing on them, recently testing 2 roller rocker system with correct geomentry on a MGB test engine as well as stock set up and as for showing actual, not theorectical, or claimed ratios, and actual lift numbers. Here's the post with pictures of the rocker arm test.
http://www.mgexp.com/phorum/read.php?1,2393221,page=1

OK here's the deal if you change the ratio, you have to change the pivot hole in the pedestal, there are vendors out there, who are offering slightly higher ratio rocker arms that can be used with stock pedestals, while they bolt up, in almost all cases roller rocker arm shaft heights has to be corrected with the pedestal shims, which most time includes changing the push rods lengths as well. If you for example buy a set of 1.5 ratio rocker arm for a 1500, this is only slight ratio increase from stock and, whe n you combine that with the pivot hole in the pedestal being in the wrong place, ever so slightly, the shaft height being too low,and the push rod length and angle being wrong, you will more than likely end up with less lift than if you had stayed with stock rocker, if you go to trouble of making pedestal shims and getting push rod length nailed, you will see a little of increase in ratio and lift number. The deal on getting a reasonable lift gain with roller rocker arm, is to go big on ratio change, like 1.65, but then on street engine you can achieve the same thing with stock rockers, and cam with more lift. Now roller rocker arm will create less friction at the valve tip,and maybe in some cases less weight, but these are normally gain a street driven car will even notice.

I charged $250 minimum to set up a roller rocker set up on engine at my shop, and this can be in full assembly like Titan offers, ore with partial system like Harland Sharp would be more money to set up, and I consider this to be the deal of deals in my shop because I may spend more than a full day nailing the geometry , getting the solid spacer to not bind at full torque, if I only take the complete assembly apart three times to get it right, I would consider this a big victory, it often times take way more than this.

In closing, I'm not going to tell you you cannot get gain from roller rocker arms in street engine, but it is way more involved that simply bolting them on, regardless of what system you buy, you will have to put the work, and time in to see that gain. On the GT6 race engine we will using the Richard Good roller rocker arms and I fully plan on testing them against stock rocker arms as for lift as I did with the MGB rocker arms, now Richard tells me I will see the claimed ratio, sorry I was't born yesterday, and that will have to be proved to me, and I'm quite sure I will not see that, but will see a gain, The problem is rocker arms ratios are not figured in real working manner, so the never live to their claimed ratio, but we will get a nice lift gain nevertheless, just not the claimed gain. This is the nature of the rocker arm and it's design, and with the high lift race cam we will be using, we will see more of ratio drop than one would with the street performance cam.



Hap Waldrop
Acme Speed Shop
864-370-3000
www.acmespeedshop.com
Engines, Rebuild Kits and More.


Member Services:
MG/ Triumph Performance Street/Race Engines - Cylinder Head Porting - Modified SU HS Carbs - DIY Engine Rebuild Kits With Free Tech Advice - Alloy wheels for British Sport Cars,and others
spitsfire Avatar
spitsfire Joe P
Redding, CT, USA   USA
1974 Triumph Spitfire 1500 "The Beast"
Here's a short list in response to the OP:
bored .040 over
shaved the head .063
flat top pistons (to yield 9.5:1 CR, give or take)
block was tanked, got new bearings, thrust washer etc. & we balanced the bottom end.
big valve head, 3 angle valve job, mild porting on exhaust side
HS4's (rebuilt by our own Dave Braun)
Lucas D22 Dist (custom curved & rebuilt by Jeff @ Advanced)
Lucas Sport Coil
Moss UK u4-2-1 SS header and dual exhaust

It's supposed to have a mild perf cam in it but I am not sure. It's been 25? years since the engine was built and the guy that did most of the work had a stroke a few years back so I can't ask him. Anyhow, the cam is next on the list. Probably do the MkIII profile cam as it's a road car. I don't want to have to wind it out every time, esp since it's a 1500 and won't appreciate it. winking smiley

Needles should be sorted in the next week or so, looking for another 10? RWHP. Running super rich (10:1!!) it measured 63HP/85ftlbs at the rear wheels. Figure +15% at the crank. Not too bad. Stock US figures for 1974 were 57HP at the crank and back then that would be on a stand with no accessories, etc. 73HP at the rear wheels would be around 84 at the flywheel. That's about a 47% gain over stock. (much less over stock EU trim of course which was quoted as 73? at the crank IIRC)

Even now it's very fun to drive. Very nice torque curve, very flat. No real need to wind it out. Reminds me of a baby version of the BMW "eta" engine. Can break the rear loose in 2nd on a tight corner. (stock I had trouble chirping 1st...)
Kind of doesn't matter where on the tach you are. I can climb 7% or steeper grades from the bottom of 3rd.
Car is reasonably quick for what it is. I can get on the highway with no issue and cruise at 70 all day.
In the real world a new minivan could run away from it, but on a tight autocross course you can eat nearly anything.

I think the majority of folks have mods in a similar vein... intake, exhaust, ignition and then go inside. The first three will get you some very easy and noticeable gains.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster