Hi Aaron. Now I know why you are interested in the speed thing!
I have a design for a speed car using 2 x 7.5cc marine engines (I cant see the pic above so dont know if thats the twin car or not) I tried using marine pipes in cars in the past and they do produce a lot of power but all at a single rev band. In a car there is very little power in the low revs and when the engine comes on pipe the power comes in with a big bang. Thats OK on a boat but with a car you need control. Here is the Alien 4
On my RRR i got 84 in 1st and when it changed to 2nd it stalled. I'm sure it would have gone a lot faster but I could not get it on the power band.
The new design is a 4 speed gearbox and bigger engines to ensure enough torque to get the thing going. Lets hope it works
If that dont there is always the 200mph rocket car!!