A few weight savings & other mods to my MGBGT Autocrosser
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- เผยแพร่เมื่อ 1 ต.ค. 2024
- Today we are taking a look at parts of my MGBGT Autocrosser that I have either modified, or built from scratch myself that are connected to the engine to either save a little weight, or (hopefully) gain a little horsepower.
We start with the exhaust header, and a little background to show how I came to build what I built. We take a look at the rest of the exhaust as well as the intake manifold, all of which I hand built too. Then we look at some parts I modified to save a little weight to reduce rotational mass and overall weight on the nose of the car to help balance it out. We also take a look at the aluminum radiator core support I made that didn’t end up saving quite as much weight as I originally hoped it would.
Watch for more videos coming up soon on getting the new performance engine back in the car plus a few repairs and additional modifications.
On a LCB manifold the step at the head/manifold flange is much less to do with allowing the exhaust gases to expand rather to stop reversion of the exhaust pulse preventing the next pulse exiting. This is particularly important at the siamesed exhaust port on 2/3. Ideally the flange should have a short tube of the port dimensions set in the manifold and the manifold fabricated around it creating a pocket to thoroughly disrupt the reversion flow.
A friend of mine rallied a Lada and in the stage rally series very few modifications were allowed and beside he was cash strapped so that to increase performance the Lada went on a diet. Every bolt was cut precisely to length to give a 1 thread showing when tightened and there was various brackets that were lightened. To assess the weight saving, all the swarf and waste ended up in a bin, which was weighed at the end to find that 28kgs (62lbs) of waste was in the bin.
As You were talking about building your own set of headers ----- you made me think of an article I read years ago about ----- tubes being of certain size diameter and the tubes being of equal length ----- but to find the -- Best -- performance length ---- the tubes were left a little long ----- they would do their runs and seems like just past the heat discoloration was the range that header for that engine was best. And the tubes were then shortened ---- something like that ---- read that sometime ago ----- Maybe someday when get your carbs back and you have that exhaust on that you made ---- it would be nice to hear what she sounds like ------ One wouldn't think that the stock exhaust manifold would ---- Flow --- as good as that guy said ----- being casted and rough inside ---- definitely heavy over headers ------ My car '69 MGB GT must have the HS-4 ----- Is there an advantage to switching to the HSIF-4 as you did? --- If anything --- can the HS-4 be made to perform better? ----- Lots of things one can do to reduce the weight of the car ---- if you get it ---TOO LIGHT----- are you put into a different class ----- Thank You for sharing on some of the things you did to make her go faster ---- Hope you have a Good Week ------ Rodney
The HIF-4 can flow slightly more air, but either is plenty (roughly 300 cfm / pair vs 310 cfm). The HIF with its integrated float bowls have less fuel starvation issues in hard cornering, yet are a bit more difficult to service as the whole works have to come off to diagnose float and dirt issues rather than just taking the lids off. ( they also have less throttle shaft wear issues due to having outer shaft seals, so less potential air leaks )
The biggest reason I use and stick with them is… that’s what I had to work with when I first set my car up, and I worked them over with thinned out throttle shafts and such…
What company made that intake? Do you think you can still find one? On the weight savings… did you go to an aluminum head?
The company is Maniflow, they are in the UK and still in business with a good sized line of products.
I almost went with an aluminum head, but I’m not sure the weight savings is worth the $$$. An addition to the aluminum head, I would have also increase the compression ratio which would’ve required custom pistons ($$$). And if I went that far, then I would’ve wanted to do fuel injection as well ($$$). I ended up deciding to not spend all that money since I spent more on the shop than I had hoped, and I do have an in progress build of a V-8 MGBGT, and that would’ve made my four-cylinder feel slow no matter what, so I didn’t do any of that
I like the inlet manifold. Do you use a heat shield the exhaust manifold an the cards?
Then inlet manifold works with the factory heat shield, and will work with either the original exhaust manifold or the header that I’m using, and I can put either the HIF-4 carbs or the HS-4 carbs on it